baby's 1 st birthday
I don't think your baby will understand much on his 1st birthday, so I believe it's going to be more adult party. I would keep it small, just inviting close relatives and best friends. The optimal location could be your home, just in case your birthday kid wants to have a nap in a middle of his/her own birthday party.
I like to have themed party for kids birthday. It's fun, colorful and you can make nice pictures. You can invite clowns, rent a jumping house and just relax.