There is so much to see in Slovenia and Croatia that a 2-3 night diversion to Sarajevo seems like a lot of time if you have only three weeks. So I guess it really depends what else is on your agenda and how do you weigh it against Sarajevo?

I only made it to Mostar on my trip to Croatia. I do kind of wish I'd continued on to Sarajevo, but it would have required an extra couple of days.

Search the forum here for more than one good report about Sarajevo (you can search back up to three years; I'm sure Julia_t's reports are still up) and read what people have thought about it. Not all past posters will read this thread immediately.

Hi,

If you interested in really seeing the great diversity of he region, then I would highly recommend a visit to Sarajevo as well. I spent a year in the region with Sarajevo as my base - had wonderful experiences everywhere.

Highlights of the region...which may be on you itinerary:

Ljubljana
Lake Bled
Zagreb
Dubrovnik - the town is beautiful to wander around; highly recommend a day long trip by boat to several of the smaller islands
Plitvice Lakes National Park, Croatia
A Croatian island - Hvar, Korcula, Brac
Trogir
Mostar
Sarajevo

Read the "Comments" section of this NYTimes blog - people discussing their experiences traveling to Bosnia:
http://intransit.blogs.nytimes.com/2011/02/22/qa-day-trips-from-sarajevo/

Some photos of Sarajevo:
http://www.flickr.com/search/?q=Sarajevo

Your travels in the region will partly (largely?) depend on how you get around - a car providing you with flexibility, and buses/trains, slowing you down a bit. What you see/ will also depend on how leisurely you want to make the trip. Some would spend 2 weeks just in the islands.

Sarajevo has great architecture and wonderful culture quite different than what you will experience in Slovenia/Croati (which are also great). No matter what you do, it will be a great trip.

Enjoy!

That really depends on your interests!

I found Sarajevo wonderful and compelling and special and well worth a visit. And there is nothing in Croatia itself that, IMHO, can serve as a substitute for Sarajevo. At the risk of misrepresenting this remarkable city, let me overgeneralize by saying that when there, you can see and experience glimpses of what was before the war, as well as what has followed. You can roam the still incredibly small and lovely and vibrant area that still holds mosques and synagogues and eastern Orthodox churches, all within blocks of each other. And you can visit various moving monuments / memorials to the war. If you are interested in history, I think you would find Sarajevo a moving testament to the ways in which diverse cultures have historically found ways to co-exist, and the terrible price that is paid for war. When I visited in 2009, I found it vibrant and inviting in the way that a northern city can be at the very earliest signs of spring, as though it, as a city, was deciding whether the bitter cold of its recent history was really past.

I found that 3 weeks - as generous as it sounds - was not enough to explore Croatia and its immediate surrounds. You might get more helpful responses if you tell us more about your interests.

We have a good friend who has been living in Sarajevo and have visited her twice in 2010 and this past fall. It is a fascinating, beautiful and haunting city, very different from Croatia. The scenery between the Croatian coast and Sarajevo over the Dinaric Alps is also very beautiful, an added bonus.

I wrote a fairly long TR in 2010 but have not managed to do much of a report on the last trip

If you don't want to travel as far as Sarajevo, I would encourage you to take a shorter trip to Mostar in Bosnia &
Herzegovina. You will get a taste of the very different culture there.

We spent time in Istria, then came into Zagreb for a few days and took the train from there to Sarajevo. For us the experience was well worth it for all the reasons others have commented on. Haunting, beautiful, unique and historical... plus we had some really great food there and met some of the kindest people we've encountered on our travels.

From Sarajevo we took the train back to Croatia (Ploce) - it is beautiful scenery on this train route. From Ploce, a short ferry ride to Trpanj where a bus meets you and takes you across to Opatija then a 10min ferry ride to Korcula and voila! you are on the islands.

We were a little intimidated to add this travel time and moving pieces to our trip but it was well worth it.

Tips: There is a great underground shopping center right at the main station in Zagreb. Pick up some snacks before you get on the train! Also sometimes different parts of the train route are under construction, if that's the case they'll off-load you onto a bus for a spell then back onto the train.

The train trip between Sarajevo and Ploce is well worth it for someone interested in trains. In October we took the section from Sarajevo to Mostar. Many tunnels -- my husband, the train enthusiast, counted them but I can't remember the total. The train itself was very basic although one car was better than the others. The scenery is really spectacular on this part of the route.
If you drive, there are two different routes from Mostar to the coast. One is more scenic and has less traffic but there are still land mines along the route so you have to be careful (See my 2010 TR for more details)