I think you are in pretty good shape. However—have you visited Eurotrip’s trip-planning feature?

Cil, I’ve just found out about it, after I posted my question. Great feature.
Thanks for your reply.

For the backpacker style your budget is very comfortable, but some things to think about….

$75 to $100 per day is more than enough for hostel dorms and adequate per person for 2 people sharing a budget hotel room. It will take some looking to find well located single hotel rooms in big cities for this. Private rooms in hostels are an option, but they’re usually doubles where you’d have to book, and pay for, both beds, so little savings over a budget hotel. Try some hostel dorms and some B & B’s and small hotels that aren’t centrally located (but have good public tansit access) to bring the average down. I suggest a guidebook designed for budget travelers (Let’s Go, Lonely Planet, Rough Guide) as a starting point in your search.

Attractions seem to generally run 9€ ($12). Your $20 a day will probably be enough, but if you’re a museum geek you’ll have to pace yourself a bit. Look for museum passes (which save time waiting in ticket lines even if you don’t save money), free days, free or reduced evening admissions, and combo offers. Today’s ticket stub from one museum will sometimes get you 1/2 priced admission at another.