You can also fax the hotel with that info. About 1 week before you arrive, send them a fax, but be creative. Give them the info of birthdays/anniversary, and the more fun you have with the fax, the more likely you are to get some action. We had read (here, I think) that if you send them a fax and make it interesting, the more probability they'll do something special. If you just sent a plain fax, they may not do anything.
We did this for my son's birthday one year, and there were balloons & an autographed photo of Mickey when we got back from a park on the first day.
By all means, when you arrive at each park, go to Guest Relations and get a birthday pin for them. It's amazing how many CMs will come up to them and wish them happy birthday. This is what happened to my son: we got him the pin. He got to pick our seats on several rides. The CM at Pecos Bill's had the WHOLE restaurant sing Happy Birthday to him. He got "special" treatment at a lot of the restaurants. He also got special notice from a lot of the characters. He'll never forget the experience he had that year.
When you make dining reservations, be sure to tell them about the birthdays/anniversary. If you've already made the ressies, call back. They do different things at different restaurants. Have fun with this!!!