I can tell you why UPN didn't do a farewell night.......
Aside from Star Trek, what UPN series is on DVD? I don't count Roswell or Buffy since they were on both networks. Also with the bitter taste Enterprise left in Trek fans, why air them? Unless you were going to tell everyone what the new movie was about.
You couldn't do the black shows since many of them ended with clifhangers and bitter taste in everyone's mouth. I wouldn't air Moesha's pilot since a cast member is dead.
UPN won the war with the WB on terms of comedies. They failed with dramas since none were really given a chance to grow (Kevin HIl, Jake 2.0).
The WB lost stream when they turned thier back on blacks, not in term of black shows, but when you go from having blacks on most of your shows (Charmed, Felicity, Angel, Smallville, Steve Harvey, Jamie Foxx as main cast members) in 2001 to one (Wesley Jonathan) in 2006. People will notice and the ratings proved it as if the show wasn't Everwood, Smallville, Supernatural, 7th Heaven, Gilmore Girls, One Tree Hill (at times) or Reba, it got smoked by UPN.