Hi all!
Ok, so I am at WDW now, and visited both BBB's today just to check them out. Here are a couple of things I picked up that are worth noting.
1 - some dresses/sizes are not available. For example, I really like the princess Tiana dress, but it is completely sold out in stores around the park. The ONLY WAY to get the dress is to have a BBB appointment and hope they have the size you want. Which brings me to #2
2 - You can apparently "request" a dress ahead of time. I am not totally sure how this works, since I got different answers from different cast members (including the one who told me about it initially). When I talked to the girl at the BBB at Downtown Disney, she said, yes, they can try and hold a particular dress/size for you, although she wouldn't absolutely guarantee anything. We have our BBB appoiintment at the castle, so she was nice enough to call the castle and add our tiana dress request to our reservation. Also note that I only have the "crown" package booked, but they were still willing to "hold" the Tiana gown for me. The FGIT at Downtown Disney told me that really to reserve a dress you have to call the boutique directly, but how to get that number is beyond me. She only had the internal number, not the one for external calls. Now, I'm not counting any chickens, but I'm hopeful we'll get the dress. However, that brings me to #3
3 - if your DD has a particular dress she has her heart set on, I might work on having it ahead of time. I ran into a girl who had just been to BBB while waiting in line at Ariels Grotto (in the rain!!!!) and they didn't have the ariel "dress" only the mermaid costume in here size, so she ended up choosing Aurora's dress. She looked very pretty, but I could tell her heart had been set on being Ariel. Now what is funny is that I have seen the ariel dress all over the park stores and downtown disney in lots of sizes... so why BBB in the castle didn't have it, I have no idea... which brings me to #4
4 - Apparently BBB gets dresses FIRST, before any of the other stores in the park. So even if it is sold out in the rest of the park (ala Tiana), they may still have it at BBB.
Hope this helps those of you planning your BBB trips. I am here until Sunday, so if you have other BBB questions I will try and get them answered for you.
Also Downtown Disney BBB seemed more "with it" than the castle folks... but that could just have been who was working the register that day.