If ribs are the only meat being served then I would figure a minimum of 3 bones per person. With chicken I think 2 is ok. If it is buffet style then look out! I watched a boy and his dad recently devour over 30 ribs between the two of them. I think the chicken will sit and the ribs will go first.
"Please let me be the person my dog thinks I am." ~Author Unknown
8 x 18 Haulmark Trailer
Fast Eddy FEC 100
Traeger Texas BBQ 075
UDS "Cool Hand Luke"
3 Weber Kettles and a Yellow Thermapen
KCBS Certified BBQ Judge #8425