DART isn't that bad. I've taken it to and from DFW a few times. Maybe relative to SF/OAK BART DART has a few more violent criminals but fewer mentally disturbed homeless sleeping in train cars and stations... So it all kind of evens out. My only real complaint about DART is that the trains on the line to DFW are so slow. A sprawling metroplex like DFW needs heavy rail rapid transit (i.e. BART) but instead has a slow light rail system...

As for places to stay, if events for this DO are concentrated around Downtown or Uptown Dallas, Uptown and the Arts District sector of downtown are pleasant and walkable. And there's a wonderful free trolley service along McKinney Avenue. McKinney Ave trolley is a great thing about Uptown.

Uptown has a nice new Marriott and the venerable Stoneleigh (Le Meridien now) one block away in addition to the Ritz-Carlton on McKinney Ave for those who like getting Bonvoyed!

There are some hotels in Las Colinas that might be walkable to one of the two DART stations around there (Irving Convention Center and Las Colinas Urban Center)