Factors to consider in menu planning?

Vary the colours and textures; putting mashed potatoes right next to a chicken breast is not as cool as putting broccoli right next to it and a roasted herbed tomato half next to your mashed potatoes. The most important thing is finding out what the people you're serving hate or refrain from for Allergies or ethical reasons. Wine is a must, but if there's someone who doesn't drink it, ask them if you can make iced tea or get soda for them or something. You don't want to take wine away from everybody else, but you also don't want the non-drinker to feel left out, so do something like get their favourite soda. Same thing with a vegetarian; if you're doing some kind of steak, also cook a slab of tofu that you've marinated in a bit of the marinade you made for the meat.