There are plenty of recent threads about Steakhouses and BBQ places.
For a slightly different experience, try some of the more unique Dallas restaurants, but what you might end up finding is that the better restaurants can't really accomodate those kinds of numbers (because of either size, kitchen, or service limitaions, for example). In this category, I'd put Lola, Aurora, and York Street.
So you might end up at more "scene" restaurants like Sambuca or Abacus, which while good, aren't great (though I'd take Abacus over Sambuca)/
You could try the back area at Hector's on Henderson.
It's large enough to accomodate the size of your group, and the food's always inventive and very good.
BBQ in Dallas sucks. Sad to say, but that's the bottom line.
I'm not sure if they can handle that many, but I'd try Daneiele Osteria first for Italian. Really nice folks. Family run, etc. If it's a week night, they can probably accomodate a big group.
I'm not much of a steak eater, so I'll leave the answer for that to others.
There are a ton of steak places here, but Pappa's Bros. and 3 Forks are good for large groups. Pappa's Bros. has the largest wine cellar in the area. As for Italian, Arcodoro Pomodoro, Mi Piaci, or Daniele Osteria are all good with decent to well selected wine lists. I'll take a pass on the BBQ since I haven't found any in Dallas that I really like, especially for a big group.