You might consider visiting the site below, which contains a tremendous amount of info regarding easy recipes, serving suggestions for hot and cold buffet, photos of how it's supposed to look [:)], and more. It also has suggested buffet food amounts for 20-50 people, actual menu suggestions, and handy conversion charts for serving 100+.
http://members.tripod.com/~lotsofinfo/
With many people being "carb conscious", you might consider providing some lower carb alternative dishes. Food allergies are always a concern when serving large groups of people. Be sure to let your guests know which dishes contain nuts, soy, or artificial sweeteners.