It's a teeny bit off topic, but you did say that you were debating if it was worth two table service credits...
We did the Princess Storybook Dinner at Akershus in Epcot (Norway) on our recent trip and it's a) only one table service credit per diner b) has a photo package included in the package instead of it being an add-on you can buy and c) you'll see a fair number of princesses there. When you're seated, you first go to a "royal room" where one of the princesses is taking pics with whoever you'd like to send in for that. It's a photopass photographer doing the pics, and you will receive an 8x10 and four 4x6 pictures along with a separate photopass id number you can redeem along with any other photopass ids you might have. Then the princesses come around to the tables and you can take pics and do autographs and stuff.
I was concerned about us finding things to eat on the Norway-inspired menu, but there is also a cold appetizer bar with cheese and salads and stuff, plus the chicken and risotto on the menu was very tasty even to my very limited and unadventurous palate.
And all that for only one TS credit each! I thought it was great, especially since my daughter doesn't have her heart set on eating at the castle specifically. So that's another thing to consider if you're looking for a princess-themed meal but you're not sure you want to use two TS credits each.
Oh! Edited to add: I wanted to put a list of the princesses who were there to give you an idea who you might find at Akershus. This, of course, can vary from time to time as Disney always says, but it should give you a good idea. We had Belle in the photo op in the royal room, then we had Cinderella, Aurora, Snow White, and "human" Ariel who circulated through the dining room when we were there.
Have a good trip!