How many side dishes are appropriate for a buffet?

[Rachel G]

I'm helping plan a Christmas party to thank volunteers for one of our local non-profit groups. The meal will be buffet style, for about 80 people. Our main dishes are baked spiral ham and roasted turkey. We have a huge list of side items, the usual southern sides, maccaroni and cheese, mashed potatoes, green bean casserole, corn, rice, deviled eggs and sweet potato casserole. What exactly is an "appropriate" number of side dishes? We have a "cook" to prepare the food, but she is not a caterer. Like I said this is a non-profit group so we are trying to learn to do some of these things in house so that more funds will go towards our charities that we support. Also if anyone has a recommendation of a book or website on catering or event planning I would really appreciate that information also. Thanks in advance!