Over the years, I've come to the conclusion that I don't need to feel guilty that I don't like to play with my kids. I mean, if a parent likes to get down on their hands and knees and play-pretend or whatever... that's great! But if it's not your style, it's really okay to find other ways to have a good time. We spend a lot of time doing stuff together -- reading, playing board games, cooking, going places (shops, parks, libraries, etc...) but I don't think it's necessary for me to be a playmate.
One positive side effect of this is that my girls have become very good at entertaining themselves. They are independent and creative and don't need an adult to engage them in play. They also learned very early how to do things like pump their legs on a swing or how to go up to other children and ask if they'd like to play...