I'd like to go for a road trip, where should I go? Have you any ideas for something challenging..?

Best I did, and I live in Hungary, was to drive around the country on the other side of the border.. went through Austria, Romania, Slovakia, Serbia, Croatia and Ukraine in a big circle. It was fantastic, mountain roads, wild nature, forest and snow. Cost a fair bit though what with fuel and accomodation also the temptation to deviate from the plan is very tempting especially when you get into croatia and serbia - countryside so beautiful it's hard to believe. So glad I did it all though :))