I love Screaming Trumpet to top off my brass libraries, especially for shakes and other tricks. It is the only library I feel that has the squealing trumpet sounds you hear in great jazz bands. It doesn't work as well for section playing though, as the trumpet sounds are often slightly sharp (as are normal squealing trumpets!) and very straight tone.
I use First Call Horns, Kick A** Brass, and Chris Hein Horns for my stuff. I love the First Call for muted brass. Also, their sounds have a little life and imperfection in them. The Kick A** Brass has some great sounds for solo use, but the built in player makes using the different articulations a little cumbersome. However, some of my most realistic trumpet solos have come from this library. The Chris Hein has no muted instruments, but it does have trumpet, trombone, alto, and tenor sax with tons of keyswitched articulations and velocity layers. (If you get good with the keyswitches, you can do some surprisingly flexible section work live!) I'm able to get pretty great results out of the box with it. The funny thing is you can get all three of these for just over $1000, and you'll have SO MUCH to draw from!
There is also a new set from Wallander Instruments (WIVI) which has some good demos (and is very affordable), but I don't know the library enough to recommend it. Garritan Jazz and Big Band has a ton of instruments with a lot of flexibility, but it takes a lot of controller or editing work (and time) to get realistic lines. It is also monophonic, so you cannot sequence a section unless you have a track for each line of music, and you can't really use it live except for solo work. (If you have the time, though, you can probably get your music closer to how you want it with this than any of the rest. I use it all of the time for a rhythm section that doesn't use much memory!) There is also the Broadway Big Band from Fable Sounds, which probably has the best sounds, but is very memory intensive and VERY expensive. (I have yet to see someone be able to create a full big band using one computer. But for solo lines or combos, it really is something else!)