I actually believe that brunch is one of the easiest types of gatherings to prepare for esp. where you can impress so easily. I have several recipes and most likely most of them are here on this sight if you do a search on them. Here are a few of the things I tend to lean towards.

Breakfast Casseroles - you can make them a day ahead (in fact the recipes I use actually call to do that) and they're quite easy. You'll probably be fine to make two. When I do two I usually do one with sausage and the other bacon or something like that for a little variation.

Monkey Bread - is always a hit and pretty easy to make. It's basically Pillsbury dough pulled apart, rolled in a sugar/cinnamon mixture and baked in a bundt pan for some shape.

Fruit Salad - if you don't see one you like on this sight let me know. I have a recipe for one called Tangy Fruit Salad that everyone always raves over.

Your basic bagels and muffins - I usually make a platter of cut up neat and different flavors of both so people can sample a few. I like to put out flavored cream cheeses and butters to go with it.

More towards the lunchy side of brunch I usually include ham salad on puff pastries. The puff pastries are quite easy to make and freeze ahead of time (search site if not I have a recipe) and I usually just buy the ham salad from our local specialty ham store.

Hope this gives you a few ideas. Like I said, let me know if you need any of the recipes.

Good luck!