I find you can get most information from the tourist boards of the cities you are visiting they are in the web
Frommers is also a good site
I also check on Trip advisor ... there are locals that can give you the best directions to places
Europe Forums - TripAdvisor
I make a word file of places & things to see & do then just print off what I need ..saves carrying lots of travel books etc...
You local library may also have travel books where you can get info