Have you considered doing the Wachau Valley boat trip and Melk as a day trip from Vienna - it is so so close and saves relocating one night - always a hassle for me at least.

Take a train to Melk, tour the abbey, traipse down to the boat dock - get off at some dock and bike along the Danube - be sure to hit Durnstein IMO - lovely wine town with a ruined castle on top of it where Richard-the-Lion-Hearted was gaoled once when kidnapped and held for ransom when returning from or going to some Crusade. It is a sweet bike ride or walk from Durnstein to Krems, a larger town but still cute - can take the train back to Vienna from Krems.

You can buy a combo ticket for Melk Abbey and the boats and train transit at the Vienna station. Of course if driving you can park at Melk and do the boat trip - or take the train to Melk and stay there overnight - a dreamy town and use it as a base for the Danube trip - you can take a bus back to Melk from Krems or even return by train via St Polten. Check these sites for good info on the Wachau Valley boats - http://www.budgeteuropetravel.com/id33.html and www.ricksteves.com.

Car rentals - Melk is a small town that may not offer many car rentals but Krems is a large regional town that probably would - you could take the train and stay in Krems one or two nights and do a day trip by boat/bike thru the Wachau Valley and then pick up car in Krems and motor on. Krems is a very pleasant city though larger than Melk - but it is surrounded by vineyards so is rather romantic in that regard.

We did it as Pal recommends, and it was a day-trip from Vienna.

The Melk abbey is not to be missed!

the highlight to moi of the Melk Abbey was an old body of some local saint or priest - just skull and bones laying in a glass case - clothed skull and bones!

Advice is based on your question-
Vienna - Meök- Hallstatt 1-2 nights

My opinion best served renting an auto in Vienna from one of the major firms-

no major rental firms in Melk or Krems

Melk has no rental agencies
Krems has an auto dealer who rents autos from his office- this not what you look for.

The rental auto opposed to train / bus public transport makes for a very convenient and effortless - time saver ands allows you the option of spensing more time where you wish - or less.

Vienna - Melk takes about 1 1/2 hours by auto

Melk Abbey is a must see - with fine Church, library and exhibit rooms - much history here and exhibits well presented -

www.stiftmelk.at


The area overall is very interesting

www.wachau.at

Melk is not the best place to stay limited selection of good accomodation and dining-

Small Danube villages like Spitz
www.spitz-wachau.at

or Dürnsterin

www.duernstein.at

fine places themselves - nice sightseeing - wine taverns and deluxe restaurants -
both places are Danube boat stops

perhaps you stay in one of these and take the boat to Melk

www.ddsg-blue-danube.at
www.brandner.at

a nic eplace in Spitz

Haus Burkhardt

www.burkhardt.at

quiet - free parking - most times in the past bikes for their guests

or use the cheap bike rental

www.nextbike.at

convenient one way drop off.

Staying in the Wachau area - a good look to country lifre - excelent local food specialties and all most probably considerably less costly than Vienna for example-

After your visit to this area
you can continue west on the roasway 3 along the Danube - nice views
perhaps a stop at the nice village Grein

www.grein.at

or Mauthausen Detention Camp

www-sacred-destinations.com

you can cross the Danube where you wish before Linz and continue journwey on the Autobahn A-1
Perhaps leave this roadway at Gmunden - following the way along the lake toward Bad Ischl and onward to Hallstatt.
This a scenic area and best seen with an auto.
After your visit in the Salzkammergut then to Salzburg and drop off the auto.
While you can do Melk and the Danube by a day trip from Vienna- with your intention to continue west - no need to backtrack - saving time and money.

The Melk Abbey has a nice little snack/sandwich shop and a lovely garden to enjoy, for a light lunch.

What a wonderful itinerary molker presents - he lives in Austria and is an Austrian I believe so take what he says with great faith. Invaluable input only a local could give.

Thank you all, I will look at this seriously in the next couple of days. We have a new grandbaby as of last night and are on duty with the other 2 for a few days. I will post when I have more questions which I certainly might.

I have decided to rent a car in Vienna and visit Korneuburg Castle when leaving Vienna. Then stop in Durnstein and spend the night, probably 2 nights. The next day we will try and boat to Melk, visit the abbey and then plan to bike back to Durnstein for the night. Will we have any trouble renting a bike in Melk for our return trip? Will I need a reservation for the boat to Melk from Durnstein? Then on the next day we will go to Hallstatt. I know that is back tracking but it doesn't seem like much of a backtrack and we will be in a car.What are your thoughts on this?

We did a similar itinerary in reverse in 2008 - it is a gorgeous part of the world! Here is an extract from my trip report

Day 5 - 7: Durnstein (Wachau Valley)
We drove from Cesky Krumlov to Durnstein in the Wachau Valley after a leisurely start to the day. The drive was lovely, especially as we descended down towards Krems – large monastery perched on the hill with the river winding through the valley below.
In Durntein we stayed at the Stockingerhof B&B Inn (www.stockingerhof.at ), which is part of a winery. Durnstein is a very small but charming village in the Wachau Valley and was a good place to be based for our three days exploring.
A highlight of the trip was when we hired some bikes from the hotel and set off to cycle along the river to the town of Melk (about 30km). It was a lovely sunny day, but very windy. We seemed to be the only people cycling towards Melk (straight into the head wind!), with most cyclists coming the other way. Was this coincidence, or did they know more about the winds than we did? We cycled through the vineyards and little villages to Spitz where we crossed on a small ferry to the other side of the Danube. The last 10 km into Melk seemed to take us forever – the winds were very strong by this stage and there were a few hills which tested our endurance. We arrived at Melk very hungry and devoured the best pizza and beer at a small restaurant in the middle of town. After this we enjoyed visiting the massive Melk Monastery. It seemed to be “dripping” with gold and most unlike any other church we had seen in Europe before.
My suggestion that we cycle back to Durnstein was met with a flat refusal. The entire family was adamant I could do it alone, so I bowed to majority rule and we returned to Durnstein by boat. The boats are well set up take cyclists, so having the bikes with us was no problem at all. It was interesting to get a different perspective of the valley from the boat and the girls identified places they wanted to explore further.
The next day we explored the valley by car. We started at the ruins of Aggstein Castle. The ruins were fantastic, the audio guide great, and the views stunning. A photographers dream! Another real highlight for us!
We then drove to Willendorf. This was a definite “must do” for us as our daughter had studied Venus of Willendorf at school, and had even made her own Venus out of clay in art. We easily found the site where Venus had been discovered and took some great photos of Claire with an oversized Venus look-alike. We finally ended up in a park in Krems for a late lunch. In the afternoon we climbed the hill behind Durnstein to the ruins where Richard the Lionheart had been imprisoned – very pleasant.

Day 8 - 10: Vienna
The drive into Vienna was easy and we were able to stop along the way for great views down over the city. In Vienna we stayed in Family Walkner’s apartment (www.apartment.at/index_eng.php3/app/66/uebersicht/). It was well located and very comfortable. The owner was very helpful providing some maps and pointing out what there was to see.
We bought travel passes for the adults in Vienna, and the children travelled for free as it was school holidays. The first afternoon we explored around St Stephens Cathedral and bought some supplies for a home cooked dinner. This was really the first opportunity where we had to self-cater and we were all starting to tire of “fries” with every meal.
On Saturday we started off at the local farmers market to buy some fresh produce – (fantastic raspberries!) and then took the tram which travels around the ring-road to orientate ourselves. We spent a few hours in the Natural History museum – a very impressive display, but our ultimate objective was to see Venus of Willendorf. She was very small and kept in a darkened room, presumably for her preservation. In the afternoon we ended up at the Sacher Hotel for coffee and their famous Sacher Torte. After this reviver we caught the u-bahn to the military museum where the girls enjoyed the WW1 and WW2 displays. The displays were well done and tied in nicely with what they have been studying at school.
After a home cooked dinner we walked to the Prater amusement park. Walking around just watching people was really enjoyable. We went on the oldest ferris wheel in Europe which gave us great views over Vienna’s night sky.
Sunday was a very warm day, and the day we had set aside for visiting Schloss Schonbrunn. The palace and gardens were lovely to explore and we all found the apple strudel demonstration very interesting. We spent the afternoon quietly catching our breath as being Sunday, most shops in Vienna were closed.

Day 11 - 16: St Gilgen
We travelled to St Gilgen via Mauthausen where we visited the concentration camp.
By the time we entered St Gilgen (about 30km from Salzburg) it was raining lightly, but even the inclement weather could not detract form the breathtaking beauty of the area. We all immediately fell in love with the place – the mountains, the lakes, the villages …. Just all of it! I personally think this must be one of the most beautiful places I have ever visited and I loved every single day of our stay, even though the weather was not very kind to us. Once again, it was a definite highlight of the trip for us.
We had battled to find suitable self catering accommodation in St Gilgen on the internet, but what we found was absolutely lovely. We stayed in apartments run by Family Weissenbacher which are next door to the camping ground which they run in Abersee (on the outskirts of St Gilgen) (http://www.birkenstrand.at/fewo_eng.htm) . The apartments were beautifully refurbished, spacious and extremely reasonably priced. This is certainly some the nicest accommodation we have stayed at in Europe, and definitely some of the cheapest! A wonderful find and I would love to stay there again!
Our first day in the St Gilgen area was an absolutely magical day! The weather was kind to us, and we headed off for gorgeous Hallstatt. We explored the town, the church and the very pretty graveyard. The bonehouse with its beautifully decorated skulls was interesting too. From Hallstatt we drove to Dachstein where we visited the ice caves, before heading for the salt mines at Bad Aussee. This was the secret hiding place of art treasures stolen by the Nazis during WW2.
Unfortunately most of the rest of our stay in this area was wet or overcast, with very few sunny patches. However, we still had a fantastic time. We visited Salzburg one day which we enjoyed. As it was a VERY wet day, we only visited the fortress and spent most of the rest of the day sheltering in shops. Our friend Andrew spent the morning on a tour of the town and the afternoon on a sound of music bus tour. We met up with him in Mondsee (outside the church used for the wedding scene in the Sound of Music) which was the last stop of his tour before it went back to Salzburg.
When it wasn’t raining we enjoyed going up mountains on cable cars for some lovely walks, summer tobogganing down some slopes (which the girls really enjoyed!) and visiting a deer park.
We also enjoyed another special day visiting Berchtesgaden in Germany. The museum, Dokumentation Obersalzberg was a wealth of information and really worth a visit. The views from Eagles Nest over the valley and the Konigsee were also special. The highlight of the day for us was however the boat trip on the Konigsee. We went to the furthermost point and then walked across some lovely countryside to another lake. It was very pretty and we took some beautiful photos to remember it by.

PRLCH, did you have a car for your trip?

Yes we did. It was part of a bigger trip - we picked up and returned our car at Frankfurt airport.