Me, DH, DD1 (3), DD2 (will be 6 months) and our spaniel all go to my parents house...
Mum, Stepdad, their dogs, DB1 plus wife and nephews (7 & 3), DB2 plus GF and niece (8), DB3 plus girlfriend. 2 sets of grandparents, uncle, aunt, cousin 1 plus husband and 3 nieces (8, 6 & 1) cousin 2 plus boyfriend. My best friend and her boyfriend, DH's best friend and his dog. Mums best friend and her husband.
Then in the evening, about 6 more friends, DH's parents, brother, his wife and their son, (1).
It's amazing and busy and I love it. My mum still manages to make a lovely long Christmas table across her dining room and conservatory by hiring trestle tables and fits everyone round it, then in the evening we have buffet style and lots of games. (When my parents had their extension they did it with Christmas dining in mind
)
Pretty much all the same people for Boxing Day too!