I would try to get in touch with the poster GoTravel as she lives in that town and her husband is a restaurant consultant.

At the risk of being rude, you may have to adjust your expectations a bit. You're visiting at the absolute peak of the tourist season. You'll be sharing the beach with literally a million visitors. You might have to wait a bit for a table.

That said, here's the best help I can give you. Relatively near the Breakers--within a mile--you'll find these decent restaurants:

New York Prime (fine dining)
The Library (fine dining)
Soho (sushi, seafood primarily)
Sea Captain's House (seafood, but other traditional items, chicken, beef, etc.- one of the few oceanfront restaurants, often has very creative lunch specials)
River City Cafe (very casual, sandwich/burger place)
Bummz (another rare oceanfront place, very casual, okay food, oceanfront deck is the main reason to go)
You should probably avoid Papa's; I don't think it would satisfy you.

Near the convention center? Realize that the convention center is maybe a mile from your hotel on 21st Avenue. But I'd say the restaurants that might accommodate a large group would be at or near Broadway at the Beach, about another 1 mile down 21st Avenue. For instance:

Landry's
Jimmy Buffett's Margaritaville
Liberty Brewery & Steakhouse
Phillips Seafood (across Hwy 17 from Broadway)

I don't like Key West Grill much.
There are other options at Broadway for a large group, but they're not my favorites either: Tripps, Hard Rock, Planet Hollywood, Yamato.

What to avoid? Any thing that has the word Buffet in the title.

Also, you may like some of the restaurants that have opened at our new Market Common: it's approximately 6 or 7 miles south of you. Access it via Kings Hwy (Business 17) or 17 By-pass. There's a PF Chang's, Gordon Biersch Restaurant & Brewery, and a very nice Italian restaurant, Travinia--we've tried and liked these. Also at the Market Common are several that are likley to be good, but we haven't tried them: Tommy Bahama's Tropical Cafe, Divine Prime, and Roy & Sid's.

Obviously, there are lots of other restaurants in the area, but I've tried to keep you within a mile of your specified locations (with the exception of Market Common).

If you venture further north, you may like these restaurants also, all along Kings Hwy: Ciao (great little Italian cafe), City Bar (sophisticated, at least for MB), Bonefish Grill (a chain, but a very, very good one), and Liberty Taproom (suprisingly varied and good menu, one of our neighborhood favorites for lunch).

Good luck!