If you want atmosphere and theming, and don't care about the food, BOG is your choice. The food is merely ok. I'd suggest doing breakfast or lunch there.
'Ohana has a Polynesian atmosphere, and is themed to the hotel, and it has entertainment (although, to be fair, it's focused on the little ones). Food is plentiful. I've had great meals at 'Ohana, and I've had meals that were not so great. The visits I thought were less than stellar typically were caused by a server who was also serving a large party and couldn't find time to serve my table of two. After the first time that happened, I learned to tell the server that we needed more attention.