There's no way I'm doing one party for both of them, even if they have the same birthday. It's not fair to either of them, but especially not to DD#1. We will be doing a bday party for her this year, but it will be small, with immediate family only (last year we went all out for her first bday, but DH's family is huge and I just don't have the energy to cater to all those people). I don't care if it kills me, she will get a bday party. Luckily I have family in town that can help if I need it. I think maybe what we will do from now on is for first bdays have a big to-do, then subsequent bdays do a toned down family party, until they are old enough to have friends at a party. At that point we will re-evaluate.
Mom to DD#1 8/04, nursed 43 months, DD#2 8/06, nursed 21 months and DD#3 9/08, still nursing strong