Where can I find a list of the top 50 tourist attractions in the
United States, with addresses?

HI Adam,
USA is a big place and tourists are a very diverse group, so the
answer could be difficult.  BUT you are in real luck, someone recently
asked much the same question and got an answer commensurate with the
price:

http://answers.google.com/answers/threadview?id=518314

These sites are probably in that answer too, they let you look for
more information at places around the country.

http://www.chiff.com/travel/USA.htm

http://www.usatourist.com/

Have fun!
Myoarin