Goodness, girl, the possibilities are endless.
You might start with gougeres. For a gathering like that I pipe the pate choux into various shapes (i.e., discs, crescents, triangles, etc.) and use a different filling for each shape. For instance, shrimp salad in the circles, chicken liver pate in the triangles, etc.
You can make the puffs ahead of time, then fill them just before serving.
Won ton cups also open a world of opportunity. To make them, take round won tons and fit them into mini-muffin tins. Hint: a shot glass will help get them started evenly. Bake these at 350F for 5-6 minutes until lightly browned and crisp. Let cool. Fill.
You can make these long ahead of time as they keep two days longer than forever in a zipper bag.
Among the ways I fill these:
1. Poached gingered pears with gorgonzola.
2. Caponata.
3. Southwestern black bean salad.
4. Tomato jam & shrimp
5. Any standard "salad" (i.e., tuna, ham, beef hash, etc.) tricked up with various garnishes.
Just let your imagination go wild. Again, make the cups ahead and fill them just before serving.
Empanadas and all the variations on filled dough envelopes are ideal. Make them ahead then pop them in the oven to reheat.
A cheese/fruit tray always works well with gatherings like that.
Peel and eat shrimp are always a hit. Put out a big bowl of them, on ice, surrounded by a selection of sauces: cocktail sauce, avocado cream, Louis dressing, etc. Depending on your mood and the nature of the group, serve them in the shells, and guests can peel their own, or pre-peel them, leaving the tails intact.
Most of all, make it stress free. If you're too busy obsessing about the food you won't enjoy your guests---and that's the real purpose of the get-together