The Joy of Cooking (1997 edition) has a kind of all-purpose quiche recipe: pick your meat (optional), pick your vegetable(s), pick your cheese, add beaten eggs and cream. But I understand you may not want to run out and buy the book if you don't already own it just for that. If you go with the three quiches idea (which I love), I would make one classic bacon and onion quiche, one with vegetables, one "ethnic"--Italian, Greek, Mexican, etc. Breakfast casseroles are good, too, although if your guest list includes at least one vegetarian you should make two.
As for whether to try new dishes on guests--I do it all the time, but I don't choose very complicated dishes, or those that require advanced skills (like de-boning chicken or flambeing something), or those that require split second timing, or those whose combination of ingredients seems weird. I tend to stay away from recipes that say "Serve immediately."