How many is too many at a party?

We are finally going to have our first big party in our house. It is a fairly conventional/traditional layout brownstone (although with kitchen at rear of parlor) 20′x45′. My question is, how many people is too many – especially given it will be too cold to use the garden? Will be mostly adults but kids too. How many have you had & did it work? How did you spread the party though the house? Anything else we should think about?
Thanks

By going4broke |