Croatia’s dalmation coast is beautiful. Budapest, Hungary where I lived twice is gorgeous. Prague in the Czech Republic is also really beautiful. Austria though more expensive, is also beautiful. The prettiest town in Poland is definitely Krakow. As an added benefit, all of those places are a lot cheaper than Western Europe. Italy is also gorgeous with great food, art, etc.
Looked at prices on different travel catalogues, including Collette Travel and CIE, and indeed prices to Eastern European countries are cheaper than Western Europe.
They even have a few trips to Israel that are cheaper than going to Britain or Spain.
We took Collette in July on a British Landscapes tour and were impressed with the service, the tour & the tour manager.