If you can, get a Guest of Honor pin with your con's name on it from the Christmas store in DTD to wear with the B-day button/badge ... then the cast members will say "Happy Birthday *Johnny*!"
In one of the shops a CM called a special # and Goofy wished my daughter (who turned 28 in Disney) a Happy Birthday.
I also faxed the resort to let them know that Vicky would be celebrating her b'day while we were there and asked if Mickey could send her a card. The card arrived, but there was a bit of confusion as it was addressed to my granddaughter, rather than my daughter ... so make sure you tell them it's Johnny's 7th birthday, LOL!
Also tell the person checking you in at Chef Mickey's that it's your son's b'day ... I believe they'll give him a special placemat.
Also you might want to make a PS ressie for the Ice Cream Social at the Garden Grill (The Land, Epcot) ... they serve special sundaes for kids and adults and Mickey and Friends visit ... all for just $7 per person, plus a tip. Remember to mention to your waiter that it's your son's b'day.
I highly recommend the Family Magic Tour. We did it last summer and had a blast ... my grandkids (7 & 8) want to do it again next summer.
Just be prepared to participate ... you'll be hopping, jumping, skipping and taking giant steps around the MK ... and collecting a few odd looks, LOL!
Don't forget your camera and autograph book ... there's a character meet and greet at the end.
Peter Pan and my grandson were very naughty ... they jumped over the fence and rang the Liberty Bell ... worst of all I almost missed getting a photo of them: