If I were you I would try not to spend too much on decotations for a first birthday. Honestly he will not remember it. I would just be practical and try to cater to the likes of the guests. I mean, if you are planning on having a lot of children, I would find things the decorate with that they will enjoy. Crayons and chalk are always a big hit. You could cover the tables with paper and just let the kids go to town. I have three kids and I can tell you that the best parties that I have attended with the kids are the ones that keep the kids busy. If it is warm out let the kids play with water. Put buckets of water out with cups and stuff for them to play with and they will love it. the same is true with sand. I think that the best theme is to just make as fun as possible. the more hands on stuff for kids to do the better. If you are looking to decorate so that the house/yard look cute. I wouls just get a few things that might match the invitation and a cute cake and you are set. My sister-in-law decorates cakes and for my daughter's first birthday she did her cake to match the invitation. I had matching napkins and cake plates and the rest of the party was all about the kids!! You might want to talk to your guests and find out what kinds of things thier kids like. Good Luck.