I've traveled in Europe several times and a little planning goes a long way,although building in some flexibility is also wise.
Next Spring I will take my first river cruise in France and I think I will go all in by sailing to London rather than flying. I will get a Eurailpass and wander around France and Italy,probably standing in line to try Stanley Tucci's favorite restaurants!
I still consult Rick Steves' guides before I leave,but with the internet,it is a lot easier to wing it these days than it was on my first trips.
Bon Voyage !