With 5 places in 9 days (you actually only have 9 days on the round - you can't count the days you arrive and depart) you don't have time for a detailed itinerary - what you are planning is the definition of whirlwind.

If it were me I would fly into Venice and out of rome and just stick to Italy - so you have a chance to actually see more than a couple of sights in each place. Unless you are planning on touring the countryside (and when would you do this?) a car is just a nonsense.

IMHO to see anything of these cities you need:

Rome - 3 days (4 nights)
Florence - 2 days (3 night)
Venice - 2/3 days (assuming you count the day you arrive)

If you actually want to see anything of Switzerland you need to add at least 3 or 4 days to this trip - and that will get you one place to stay with a couple of day trips.

As for a DETAILED itinerary - for that I think you need to pay a travel agent.

I agree that your preliminary plan is very ambitious.

You can go through the mountains on your way to Italy, but if you really want to spend some time I would recommend catching a train from Zurich to Luzern. I think that is only about an hour by train. Luzern is very scenic, but to best see the mountains you would probably want to take a daytrip to Mt. Rigi, which has superb views. An alternative would be to go to the BO above Interlaken. Lauterbrunnen is at the bottom of a beautiful valley, but there are small hotels with mountain top views in many of the villages above Lauterbrunnen. I think this would take a lot more time than Luzern.

I wouldn't get a car. Many of the places you list (Florence and Rome) are full of insane drivers, while Venice and many Swiss villages do not allow cars. You can get wherever you want to go via trains much quicker.

In Switzerland, most of the best hotels are in the big cities, or in the ski resorts, at the bottom of the slopes, so I think a mountaintop view from a hotel is a bit of a reach.

I would look more into the cost of a train pass; trains in Italy are relatively inexpensive, and you will be in Switzerland a short time, so you may not be able to exploit a pass. Once your itinerary is set, look up the cost of point to point tickets; then see if there is a pass that will benefit you. Some people use http://www.railsaver.com/ to do this.

In Italy, I would omit Rome in favor of Florence and Venice because of the length of your trip. Rome is so big it deserves at least a week. Pisa is an easy half-day trip from Florence. Venice is best at night after the cruise ship crowds leave, and is a convenient place to fly home from, although it seems every flight I get there leaves before the sun comes up.

Thank you both for your feedback. I am strongly considering your suggestions...
nytravelor - we looked into flying into Venice, but the cost was much more and we are flying into Zurich for free(airline miles). At this point, we are thinking just one night in Luzern, then taking a train to Venice the next morning.

clevelandbrown - Are there any views of the mountains in Luzern? Also, do you know much about train routes from Switzerland to Italy - are there certain routes that are more scenic than others? I've heard of the Gotthard Route, but can't seem to locate options using this route.

There are direct trains from the Zurich airport to Luzern--one hour, with no changes. Luzern is on a lovely lake and there are mountains around it, but not the high peaks you are probably thinking of. You could get lovely views by going up Rigi (if it is clear); you get there by boat and then either a cable car or cogwheel train. This might be a bit much after your overnight flight from he US.

To go form Luzern to Venice, you head first to Milan. You can buy discounted tickets for the first leg (from Switzerland to Milan) on the Swiss train website, www.rail.ch. The train originates in Zurich but if you are in Luzern you can join it at the Arth-Goldau stop. The cost of these tickets (starting at Luzern) is 37 CHF instead of the regular price of 86 CHF. That price includes your required seat reservation.

This train travels the Gotthard route which has some tunnels but not a really long one that misses all the scenery. IF it is clear (a big IF) you will get glimpses of lovely mountain scenery.

This is really your best option for a relaxing day on arrival and a quick and inexpensive trip into Italy.

The other option, with better alpine scenery in Switzerland, would be to head right away from the airport to Lauterbrunnen (2.75 hours, 2 train changes.) You need to get up to Muerren to really have the views, so add some time for a cablecar ride and then a short train. You end up perched on a bench high above the valley, looking right at the Eiger, Monch and Jungfrau from various points nearby.

From here you would travel to Milan by returning the INterlaken and heading west to spiez, where you catch a train to Milan (there are direct trains if you hit it right.) this route goes through several Looooong tunnels through the mountains, so the ride itself is not as scenic as the Gotthard route.

Given the iffy nature of the weather, especially in April, I think you are better off with the simpler and shorter journey to Luzern, and the Gotthard route to Milan.

You need to get to Milan regardless where you go after that---Venice, Florence, etc.

In April you may still get a lot of snow in the mountains.

If you decide to visit Lucerne you can make a visit to one of the nearby lower mountains (Rigi, Pilatus) - about 7,000 feet only - by cable car or cog railway. but do check the timing of these - these don;t run all year. Also realize that the mountains are high enough that you can be stuck in the clouds and see nothing from the top - even if the day is clear in the valleys.

But- you still don;t have enough time to see everything that you want - I really suggest you drop something - Venice or florence - if you are determined to visit Switzerland.