In my opinion, most restaurants have great desserts for adults.... For kids... it's a different story now that they changed the kids meals for the "healthier" versions, which happened about 5 or so years ago...but in my family's opinion, the kids meals are HORRIBLE...so we tend to go to a few served restaurants with mostly buffets so the kids can have their choice of the meal they want to eat....
Some of the places we've found to have good dessserts for kids...
BOMA...they enjoy a few of the "different" foods and have a huge array of wonderful desserts the kids enjoy..and the "big people too"!
Another place they enjoy is Liberty Tree Tavern for DINNER...
Cape May has an fair dessert selection and a Huge Buffet which we all enjoy...fish lovers AND those who don't care for fish....
Ohana would be fun for the kids with the singing and games and they will be able to have a good dessert there....
At Whispering Canyon Cafe, my grandson was able to get a milkshake in place of dessert so that was a good treat for him...
Downtown Disney's Wolfgang Puck Cafe has a Beautiful menu for kids...not only the meal but the dessert options also....
That's about all I can think of for you that would serve a good variety for meals AND desserts other than the typical cookie/vanilla sundae type of stuff...