Jazz, swing, easy listening, oldies (is that even a genre?)??
The second one is, do you label your rap/hip hop albums as rap only, hip hop only or you don't really care about that. I wanted to tag all hip hop albums as rap but it just doesn't feel right.
Frank Sinatra, probably depends on the album. If you check out Last.fm tags + Discogs tags + Rateyourmusic tags for the albums, or the artist, you should be able to merge them together to find the most relevant ones.
As for your second question, multiple tags (: Most accurate one first, then the rest! Then they'll all turn up in your search, but if you want to arrange by genre you still can. That's how I do it anyway.
Get Your Damn Tags Right
2 questions that have been bugging me