I am throwing a 25th Anniversary Party for my Parents?

There are 30 people coming, I am getting the main dish catered (chicken parm, ziti, garlic bread) and I have a cheese platter, small appetizer meat, tossed salad, rolls, a sheet cake, cookies, and brownies. I feel like this isn't enough, alot of the guest are offering to bring things, but I don't know what to ask for that would go with the meal, I figure I should have 1-2 more appetizer type platters, and maybe another dessert or 2. Any suggestions would be much appreciated.