Saturday dinner in PIT
In that area, they're all chains except for Scoglio's, which is the best out there. If the folks are older, they probably like Red Lobster or Olive Garden. If it's a large group, you'll have a good time at Buco de Beppo. You probably won't find much you haven't seen before.
Hardly anything anywhere is stuffy these days.
Apart from Scoglio's, a couple are local chains, Mad Mex and Atria's. Never been to Atria's, but Mad Mex is fun, Mexican-type cooking but some unusual tastes and ingredients. Not authentic, but not trying to be. I mean, thai curry burrito, anyone? ;-) http://www.madmex.com/
If you must go to the group of Darden Chains (Olive Garden, Red Lobster), at least try Bahama Breeze. It may not be as good as it used to be service-wise (used to be a notable step above the other two, but last time we tried it it seemed to have fallen off), but the food is atypical for such a chain. Tastes would be at least a little out of the ordinary.
I dunno if anyone here has been to the Red Bull Steakhouse, and I haven't either, but that could be an option. I dunno if it's "not stuffy", but I wouldn't think it would be, as yayadave said, hardly anything is stuffy now.
In another year there will be more stuff with a new development, but that will probably mainly bring more chains....
There's also the North Park Clubhouse, which is a chain of 2, dunno how current the info is. It's a little eerie to see the messages from the owner who died a couple years ago. http://www.nplclubhouse.com/ This would be the extreme opposite of stuffy. ;-)