Car Rental in Eastern Europe

I have been thinking about visiting Eastern Europe this year and my girlfriend suggested we make a little tour, and visit several countries, like Hungary and Czech Republic, maybe Poland. Do you think it is a good idea? We will stay for a week in each country and we plan on renting a car.

I think that it is a great thing to have so much time free and dedicate it to traveling. Eastern Europe is interesting for sightseeing and countries you have chosen, with their capitals, Budapest, Prague and Warsaw, have a lot to give to tourists that seek for stylish architectural buildings, museums, monuments of WW2 etc.