Rebel Dip and Gary's Two Mile North.
It must be casual date night. ;-)
After moving to Gulfport in 2000, it took me years to allow myself to eat at any establishment with Rebel in the title.
Anyhoo:
Thumbs up for Half Shell Oyster House (at least, in Gulfport), Ruth's Chris (Hard Rock - Biloxi), & Saluté (Gulfport). Vrazel's was where my wife and I annually shared our anniversary, before closing. BR Prime (Beau Rivage - Biloxi) is my choice, when atmosphere is the emphasis.
Trapani's (Bay St. Louis), used to be one of my favorites for local themed seafood. It's like New Orleans meets MS Gulf Coast. Like the Fried trout, topped with crawfish etoufee. The Paneed Chicken Italiano is Chicken Parm. done right. Their Red Gravy is a big, big plus. But, since Katrina, it has become inconsistent. Service is always very slow, and the atmosphere is noisy and somewhat casual for anniversary purposes.
Faux-suggestion: If you want to spend less than $20, take her to Brooklyn Pizza (Gulfport) and then tell her you can fold her like the pizza. Sleeping in the hall may ruin your anniversary. But, you'll remember the pizza.