HMmmm. . . I think there are a lot of variable in this question. Depends on the size of the group (big, small, intimate, all people we know, etc.), the location (home, dungeon, private play space, rented public area), how involved the evening is going to be (catered, pot luck, finger foods, no refreshments) and what my role would be (am I acting as Dungeon Master, etc). To be very honest, if I am the Host of such a gathering, I very rarely expect to play or participate other than to make sure everyone else has a good, safe, sane and consensual good time.