My DD has done the Tea Party three times - she LOVES it!!!! She'll be back in October - and she's trying the Tea Party again, as well as the Grand Adventures in Cooking!
The first two times she went to the Tea Party, it was all girls. The last time, there was a little boy about 4 or 5 yrs old. He seemed to have a good time! All the kids were having a great time as we went to pick them up!
My little girl said they read a story, they decorate a cupcake (you spread the icing with your finger!! - She loved that part), they crawled around in the restaurant, and took pictures with Alice and the Mad Hatter. It doesn't seem too "girly", but I could see where older boys might not want to attend.
Good luck deciding! Enjoy!!