For my money, I'd head back to Florence. It's compact and you can easily hit all the biggies in a couple of days. Don't miss the Boboli Gardens or going to see the David.
There are also several great day trips to take, like Siena, or San Gimingano, you can head to Cinque Terra for a day of beach hopping.
The people in Florence are the friendliest you'll ever meet. The food is fantastic. There's so much history condensed into such a small geographic area.
I lived in Europe for a year and half in college. If you are looking to spend minimal cash and party a lot, by all means, go to Prague. If you want a great beach spot I recommend Lagos, Portugal- also extremely cheap and always sunny and gorgeous. Also GREAT cliffs for cliff jumping. For fairytale-land beauty, check out Sintra, Portugal or Ronda, Spain. Those are the two cheapest, most unbelievably beautiful spots in Europe that I've found. I truly could not even believe they were real. Spain and Portugal are my favorites for relaxation and escape. The best places to go also largely depend on the time of year you go. Spring is the best time of year to see anywhere in Austria- breathtaking.
My fourite place was Rome. It was the most amazing city in the world I have been to if you include the Vatican city in it.
the cinque terre in Italy it is so beautiful and very relaxing. Barcelona is too busy if you want to relax this is your place. It is also quite cheap and the food is amazing
Rome is lovely or florence or budapest, (prague is really busy nowadays)
My vote is Croatia. It's getting a lot of press but you still have a chance to get there before it goes too crazy. Beautiful coast, lots of history, and in May or September, not too many tourists....
Just in case your heading to Korcula or Dubrovnik this summer.
Here's a good link to a cool travelers' bar called Fresh.
florence or venice for a 4 day trip would be good or also poland is nice
Not sure if it is considered the best place..( many best places in mind ).. I will agree with going to Prague... Cool!
Moscow is one of the nicest places in Europe. I think a lot of people are afraid to come here because of Moscow's reputation as one of the most expensive cities in the world, but very good deals and bargains can be had if you plan your trip out before hand. I know a lot of college kids from the US and Britain pass through Moscow every summer hiking through Europe. I am an American who has been living and working here for the last three years, and it always amazes me at how much there is too see and do here at next to nothing as far as costs go. If you come to Moscow, you'll never regret it.
My choices...Vienna or Venice. Both places were just 'on the way to somewhere else' during 8 weeks in Europe last year but they were my very favourite places in the end.