My boys' birthdays are in different months but they're 3 weeks apart. I take advantage of that and plan one party, but we often have two themes to compensate for different interests :-)

My boys' birthdays are one day apart! When they were young I did separate parties for them on different weekends but the fast few years we've done one party and they each invite their own group of friends. They are only just shy of two years apart so we've been able to find something they both want to do and it's a lot less work! One thing I've always done is I make each boy their own special birthday cake. It's something I like doing and they get a unique part of the day.

My 13 yr old and 5 yr old are one week apart. Because of the age gap, we do separate parties for each one, but typically do a joint birthday party with family (so yes, that makes 3 parties!). We keep it all pretty low-key though, and we let the 13 yr old plan his own party which is usually just a special outing with a few friends.

I only have one child right now, but my sister and I grew up with birthdays two weeks apart, and my parents were always great about making them separate celebrations. I think if I end up in the same boat with my kids, I'll likely do the same!

We like to give each child its own time to celebrate so we don't share birthdays. And sometimes birthday party is replaced by a special outing. We leave the decision to the kids, after all it's their day and their choice on how to celebrate it.