Too much planning?!?

[jilly]

So I'm planning a first time trip to Europe (3 weeks in September) with my boyfriend (we live in NYC). We want to reserve private rooms and I'm an over-planner... which means I'm getting burned out before we even start. How much planning should I be doing? Is it better to wing it? Should I consult a travel agent?

Also, I'm having issues with train distances... with longer trips (7 hours for example), it's better to do an overnight trip, right? And how do I reserve sleepers/couchettes?

I'm so excited, but I'm getting really stressed. Anyone have advice for nervous backpacker virgins??

Thanks!