What Eastern European Country for 4 days?

Turkey, hands down! exciting and half as expensive as most European countries.

Already been. :)

How about southern Poland? Great sighteseeing in old town Krakow and nearby mountains at Zakopane have fantastic hiking possibilities.

What about Slovenia and the Julian Alps for few days because we are goingto be in Kitzbuhel, Austria and then we are heading to Venice after Eastern Europe. So i am trying to also pick something that logisticlaly works.

Sounds fine. Let us know what you thought of it when you get back.

Slovenia sounds like a good fit. Have fun!

Slovenia is wonderful, and I would highly recommend it. I've stayed in Bled a couple of times and did some long walks while there. One I really enjoyed was the trip to Vintgar Gorge. Took a bus plus a walk to the main entrance, and then at the end of the gorge, rather than returning to the main entrance, took the path through the woods and country roads back to Bled. It was a very enjoyable afternoon. If you have a car, you'll have even more options in the Julian Alps.

I would suggest Slovenia or Hungary. There are more substantial sights in Hungary, but I found the Slovenian Countryside and especially the people much more pleasant and enjoyable. Especially if you are looking for hiking. Bled is a fantastic destination and I think there are some day hikes in the area, or at least good swimming. Ljubliana is a very small but gorgeous city that took me a day to cover. The people speak English and the food is great. Make sure to try Burek (That's how it's pronounced, I'm not sure how it is spelled) in the open air market in Ljubliana and the cream cakes in Bled. Plus Slovenia has some alpine territory.