Poland et al

How about Krakow to Kiev with Wizzair??
Just a few €'s one way and a wonderful city.

Well, I can see flights on skyscanner Warsaw - Split return for under US$200, so I'm not sure what your budget is, but that seems pretty good to me. Croatia is beautiful and well worth it IMO - esp. dubrovnik and and island (probably enough for a week).

In a week Warsaw and Krakow (including Auschwitz and Salt Mine) would probably be enough. You could add a day or two in Zakopane if you wanted - that would be a full week but doable.

There are so many places to go for a week in the region without flying - although just about all of them will cost at least that flight amount to get to by train. Prague is probably the obvious choice. Or I liked Budapest. Hmmm, out of those, I would still choose Croatia - I loved it there. But it depends what you're after.

Sounds like a great trip - Poland is fantastic. As other poster said, Zakopane would make a nice 2-day trip -- highly recommended if you like the great outdoors. The Tatras are beautiful, town is charming, has good restaurants, decent bars.

Re: other destinations:

-- Prague (if you haven't been there) is an easy 8-hr train ride from Krakow.

-- The Baltics can be tricky to get to - they look close, but aren't really convenient unless you're flying. The one rail route I recall traveled through the northeast (via Suwalki??) had inconvenient times and was very long, but maybe that's changed. whichbudget.com search engine is worth a look.

-- Wizzair is great and flies from Warsaw's main airport (1/2 hour from downtown) all over europe for not much $$; however note that the Krakow flights actually go from Katowice, which is about 1.5-2hrs from K. via shuttle bus, so somewhat inconvenient. But if you got a great deal, may be worth it.

-- Croatia's well worth visiting too, if you can swing it, but keep in mind that distances can be far (i.e. from Zagreb to Split). I loved Dubrovnik, Korcula, and Hvar; Split's cool too. Hvar's the easiest island to get to--maybe an hour or so via high-speed catamaran from Split, then you can go from Hvar to Korcula, K to Dubrovnik.

Edited by: sweetbeak

Just to point out you might like to take a train from Warsaw > Zagreb via Vienna - every day around 100 euro, leave Warsaw early morning, arrive Zagreb early evening... The scenery from Vienna > Zagreb is quite impressive, and a nice way to see it...

The above suggestions are good, but I can say you can easily spend two weeks in Poland. In addition to Krakow and Warsaw, Gdansk and Sopot are well worth part of the second week. The organ in Oliwa, a suburb of Gdansk, has daily concerts and well worth a visit. Also, the teutonic knights castle at Malbork is great! Add a night in Czestochowa to get a feel for the religiosity of Polands people is wonderful. Some must sees in Warsaw is the palace of Wilanow built by Jan lll Sobieski, the Warsaw Uprising Museum is a must, the Royal route, its all worth your time. Wadowice is worth a day trip to see where the pope grew up is nice. If, If you decide on only one week, when I went to Wilno (Vilnius) a few years ago, there was an 11am bus from Suwalki, Wilno is a lovely city certainly worth 2 or 3 days. If you plan to go one day to Croatia it is worth 2 weeks including 3 days in Ljubljana, Slovenia, day trip to Bled.
Have fun whatever you do, just don't try to do too much as far as distance and waste your time.

I would also recomend to spend two weeks in Poland. There is so many different places to see. Often it is recomended to spend in Krakow at least 4 days. I recomend to visit also Eastern Poland - wonderful old Lublin, renaissance pearl Zamosc town, Przemysl old city.
In Northern PL (it is very different from South) go for example to Hanseatic Gdansk (+Malbork castle), Sopot sea resort, Mazuria lakeland (lakes, castles), old gothic Torun (city where astronomer Copernicus was born) etc.
Lots of places to enjoy during 2 weeks.

I agree that two weeks will go by quickly in Poland alone -- it's huge and there's so much great stuff there. But I also understand the desire to visit other countries. It really depends on your style -- how relaxing you want the trip to be, and how motivated you are to see Croatia/wherever else.

If you do stay in Poland, I second the suggestions re: Gdansk & Torun, Zamosc and Lublin, Warsaw Uprising museum is outstanding, Wilanow is cool, and Zakopane. Also, Wroclaw is fantastic.

I wouldn't endorse that Poland is huge.
You can cross it in well under a day by train, bus or car - in any direction.
There's so much to see and do there though.
My choice would be to do Poland - and a chunk of Former East Germany.