Since Sweet Willie has bumped this thread up, and since I'm going to Dallas next week and so was searching the subject, here are my favorite restaurants when I'm visiting Dallas:

For steak, most definitely Del Frisco's. Huge servings, including some very tasty sides, and most excellent beef.

For seafood, Cafe Pacific (24 Highland Park Villsge, Cross Street: Mockingbird Lane). A bit pricey and a bit elegant, but good.

Since I'll be there for four nights this time, I'll have to try some of the other suggestions listed in the thread.