We're currently planning our third birthday trip, and planning the extra special touches is so much fun! DD turned 6 at Disney, then DS turned 10 on the next trip, and our May vacation is for both my and my mother's birthdays (8 days apart).
Make sure you book a birthday dinner at a Grand Floridian restaurant, because their bakery makes the best cakes! We loved the cake we got for DD's birthday dinner at GF Cafe. The one we got on DS's birthday at Kona was good, but not nearly as beautiful. My mom & I are having our birthday dinner at Narcoosees on our arrival night... Lobster and cake with a view of the castle... Life doesn't get any better!
Would your DD be interested in the Bibbidi Bobbidi Boutique? That was one of DD7's favorite Disney experiences, particularly since we booked lunch in the castle for right after her makeover.
If you're looking for something less frilly/made-up looking or less expensive, the barber shop in MK does fun hairdos with colored gels and "pixie dust".
How old is your DD? For DS11, we did a tour that I knew he'd love, but most of them do have age restrictions - you have to be 10 for the trains tour we did, but the minimum age for many of them is 16.
The Disney Florist has some neat gift baskets. We ordered DS a pirate hat full of chocolates for his birthday trip, and I'm ordering a Mickey kitchen gift basket for my mom for her birthday because I know she'll love the Disney Chefs' cookbook.
Before every trip, we surprise the kids with new pins for trading. I'm on the wrong computer to pass along the link to the site I buy from (sadly, my laptop died and is in the shop), but we've been able to find starter pins relatively inexpensively to get them started.
For DD's birthday trip, I made a custom autograph book with birthday decorations, which got some neat notes from characters who noticed the birthday theme.
(my daughter 
and I 
celebrate our birthdays a day apart. My question to you guys is what cool ideas or suggestions can you offer? I know about the character dinners and the cakes, Is there anything else? 
Thanks for the great ideas's!!! My daughter 
