Would like 3 sources for an architectural tour of the USA (Canada
could be included or not). 200 or more sites in the tour. eg Getty
Museum, Empire State building...  Sequence or time issues not
important, it's the destinations I want.

I am not sure just what you want.  Would you like us to provide a list
of 100 American famous architectural edifices?  I am sure that
together we can come up with some lists that would meet this simple
request, and many more.  But the field is quite broad.  Can you define
more closely what you are interested in (or NOT interested in), for
example:  20th century only; post 1850; only buildings  (not the
Brooklyn or Golden Gate Bridges), and so on.

Here is a site that could help you:
http://www.ipl.org/div/subject/browse/hum20.10.00/

Maybe also this one:
http://www.cr.nps.gov/hps/pad/adventure/contents.htm

Please let us know how we can help you.