re: Looking to take a trip across Europe...

London is expensive, but there is a shite-ton to do. You could be there for weeks and still not do all you want.

Paris I was bored of after a few days, honestly. I'm sure there were some great things that I missed, but after the main attractions the biggest appeal was just good food, which you can find all over.

Rome I really enjoyed, would definitely go back. If you are into history or architecture you could spend weeks there and not get bored.

I'd highly recommend Munich, or just Bavaria in general.