DD's birthday isn't for a few months. I'd like to invite all her little friends and their parents and our families. But, I know a 3 yo party is deathly boring for almost all the adults w/o a kid there and even my tween nieces and nephew. No one, of course, has ever complained to me. But, honestly, I feel kinda bad that they come and have to sit through the party (not that I didn't go to their kids parties when they were little). But, having 2 parties - a family party and a kid party just seems like overkill too.
Re: way ahead birthday party question
Yeah it can be boring, but they don't have to come either...I wouldn't stress about it if I were you...they know what they sign up for when they see the invite.
If you are still concerned try to do something the adults would enjoy...what about a movie party or at the ice rink or having a volleyball net up...so that the kids can do their thing and the adults can do theirs...
(you said few months so I'm thinking fall/winter)...but an ice rink party is fun!!! Our local rink does LOTS of parties and there is on-site rentals, and each kid(under 5) gets an orange traffic cone and can go on the ice in their sneakers... you get the rink to your own party...so the adults can skate while the kids do...