Very different options!

I visited Mostar in 2009, but did not get to Medjugorje. I loved Mostar, but found being there very bittersweet, as the signs of the war that ravaged it in the 1990s were still evident. But the old bridge (Stari Most) has been beautifully rebuilt, as have a number of mosques and ottoman-style houses, and the setting is stunningly gorgeous. I'm definitely glad to have been there.

I also visited Perast and Kotor in Montenegro. The scenery was beautiful and I enjoyed roaming around both places. I didn't think they are as different from southern Croatia as Mostar.

Hope that helps!

Last year I was in Dubrovnik for 8 days and have taken few Viator tours including the Montenegro ..I wanted to take the Mostar tour but I had to cancel it.
Viator has two different tour for Montenegro.One tour is more coastal much easier,the scenery is also beautiful.. the other is the mountain tour.
Viator is a good company and their bus drivers really knows how to drive.

In Our Montenegro tour we had to ride up the mountain and at times was quite thrilling because the road was wide enough for one bus to go by and the smaller cars that came from the other direction had to back up until they found a small opening on the side .

Sometimes the bus had to do the same thing if another large vehicle was approaching from the opposite direction.

I remember well the mountain curve also.Wow..

Thanks so much! This really helps. I'm really excited about Mostar in particular...it looks really unique and beautiful.

I think the answer here is: I should find a way here to do both, ideally. : )

BTW, if you can find a bit of extra time, I'd strongly encourage you to spend a night in Mostar. It's one of those places that is IMHO infinitely better after day-trippers have left/before they arrive. Watching the sunset from a gorge-side table with a spectacular view of the Stari Grad and coppersmith's road and various minarets while sipping a glass of wine and listening to the calls of the muezzin.... Doesn't get much better! You can get there by public transportation; no need for Viator.

I agree with the last post recommending an overnight stay in Mostar. We took the train there from Sarajevo last fall, arriving in the morning and left the next morning by car to Split. I think there are buses from Dubrovnik in addition to the day tour buses.

We stayed at a very nice small hotel, the Muslibegovic House
http://www.muslibegovichouse.com/

It can be very hot mid-day in Mostar and temperatures are better in the evening. And, as mentioned, the city tends to get very crowded with day trippers.

Ay recommendations on how to get to Montenegro by train form Vienna or Istanbul (travel time, cost, etc...)??

You should definitively visit Herzegovina, as you will probably have no time to visit Bosnia. Herzegovina is great - with its great weather, places to visit. For example, in Mostar, you can see so many great things, such as the Old Bridge, which used to be the largest bridge in Europe at that time.

normajean is absolutely right, Mostar is in Herzegovina, not Bosnia.

It is all rather confusing,but here is a brief summary...

Bosnia and Herzegovina – as the name suggests – is a country made up of two regions, separated by the Dinaric Alps, with Bosnia to the north and Herzegovina to the south.

They each have their own unique cultural histories but share many similarities in language, ethnicity, culture and identity.

Even more confusing is the fact that Bosnia and Herzegovina is a single country consisting of two entities, one of which is The Federation of Bosnia and Herzegovina, and the other is the Republic of Srpska. And each of these entities includes part of Bosnia and part of Herzegovina!

The name of the entire country can be referred by the abbreviation of BiH, but each region is individual. It is not all Bosnia, and the Herzegovinians rightly feel excluded when their region is not acknowledged.

You say you are going to Italy and Croatia for a total of two weeks. How much time do you have in Croatia, and are you staying anywhere other than Dubrovnik? That would help us give you better advice. We spent 4 nights in Dubrovnik (plus 2 Korcula, 2 Split) and were able to fit it both the tours you are considering. We used Atlas instead of Viator but they seemed pretty similar. Actually the Atlas tours leave out at least one 'stop' that the Viator tours include, and even at that you don't get all that much time in each place.

The Mostar one will be the most different from Dubrovnik, as there are mosques, and that bridge is totally unique (and beautiful). The Montenegro one goes along the coast which is similar to the coast in Croatia, and the city of Kotor, it's main stop, is similar to Dubrovnik (although not as large or quite as beautiful). So if you could only do one I'd do Mostar.

Although you can do all that by public transportation, or rent a car and do on your own, if you are short on time, which it sounds like you are, the tours are much more efficient. I generally hate tours but these weren't that bad. In Mostar once we got into the town we ditched the tour guide and had more time on our own to explore.

http://www.pbase.com/annforcier/image/146293865