Not only am I an only child, but DH has 2 families to coordinate. How do we deal with it? Well, for the first few years it was hard. My mom wanted me for every conceivable holiday. That just couldn't be. Now, we've figured out a rotation schedule.
Whoever is first to request Thanksgiving gets Thanksgiving, but then they don't get first choice at Christmas. DH's mother's family comes to our house a couple days before or after Christmas for their family dinner, so they don't get a Christmas vote either. Whoever didn't get Thanksgiving gets to choose whether they prefer hosting us on Christmas Eve or for Christmas Day dinner. Christmas morning is alone at our house (DH insists upon it). We'll continue like this for a little while longer, but in a couple years we'll be having kids. Unless DH's half sisters (one married and living way out of state, one recently divorced and single, and one still in undergrad) randomly end up having kids before then, we're going to be the sole progenitors for all 3 families. Then, by the love of all that is holy, they can all come to ME for Christmas!!! Have grandkids and great-grandkids...will not travel.
Easter is not a big deal for DH's dad's side, DH's mom side does an annual brunch, my family usually does dinner, so seeing as how none of us have church services to worry about we catch brunch with DH's mom's family on our way down to my parents for the evening. DH's families don't really do birthdays, so those are usually with my parents, as is 4th of July, because my parents' club has special events. Anything else is a non-family holiday.