I am a huge Jazz fan. I have a library of several thousands titles, many are what I consider mainstream Jazz.
There are dozens of labels that turned out great music by well known Jazz artists. But if I had to direct you to what I consider the mother lode, it would be the two site links below.
http://www.bluenote.com/http://www.fantasyjazz.com/If your taste runs more to abstract Jazz, this company has some of the best ever recorded. I have one complete shelf of their offerings too.
http://www.ecmrecords.com/Startseite/startseite.phpIf your in the mood for easy going contemporary Jazz that doesn't come off like elevator music, this company has recorded some excellent artists. I am particularly fond of their live on location work.
http://www.concordrecords.com/For the most complete data base on these greats, including everything they recorded and who they recorded with, follow this link.
http://www.allmusic.com/This is my favorite music information site, it has light reviews, comments about the artists style, their influences and followers.
You should be able to come up with enough great material to keep you in your music chair for a week. Good luck with your quest.