The absolute best place to get a cake from is Golden Delights Bakery. They have this kiwi strawberry cake that is "to die for". It's basically the moistest yellow cake with kiwi and strawberry inside with whipped icing and more strawberry and kiwi on top. Plus they have themed cakes that they airbrush the design on.
Golden Delight Bakery
1516 Bethel Rd
Columbus, OH zip code
And what I did for my son's Thomas the Tank Engine birthday last year was to make up posters (letter size) with 4 places to place stickers and called it Rez's Thomas Adventure and each activity we did the kids all got a Thomas sticker to put in the respective spot. The activities were, pinata, eat cake, craft activity (I found these train picture frame mosaics), and open presents. That way it was easy for me to keep the party going with the kids that were invited and keep it organized.
OK I hope this gives you some ideas or spurrs your imagination on.