I cannot speak for 'Ohana because that place is so stinkin busy, but I would bet you a buck you would have a blast at Garden Grill! If I was dining alone, this is one ADR I would make based on the way the CM's and the characters interact with guests. The characters snuggled into the booth to "play" with my DGD, made a huge commotion over my adult niece, who I think was happier than the little one! and stopped at our table, as well as the surrounding tables multiple times. Our server seemed to be way more relaxed that the servers at other character meals.
I think that the systems that are used to make ADR's are simply systems, and while they may not be programmed to make solo ADR's, the people who implement those ADR's are. LOL! Please don't shy away fro GG, it was a favorite based on way more than food.