I always find a massive piece of happy pork, stuffing, apple sauce and lots of soft rolls always goes down well. Plain green salad and some potatoes roasted in the fat top it off nicely with relatively little work, expense or faff.
Or, for something a bit more upmarket, get a lovely big piece of beef, cook it really hot and fast so it's still quite rare and let it go cold. Serve it sliced with some tarragon mayonnaise, potato salad, a nice spinach salad and some good bread.
Having done many such events in the past, I find the best policy is always to do plenty of a few things rather than lots of little bits of everything (quiche, sandwiches, sausage rolls, vol-au-vents, chicken, salads etc., etc.) It's hard not to get carried away and a) massively over-catering and b) working yourself into a stressed out frenzy!
Nigella's Feast is always the first thing I turn to if I'm stuck for inspiration for this type of thing.