I agree that Hoop De Doo would be a blast! It is really fun, they have breaks from the show throughout the dinner so you can talk and socialize with your group, they do a great job of celebrating special occasions (part of the show) and the food is good, and very plentiful.
Even though it is 2 TS or more expensive OOP, I think it is worth a special occasion such as a 70th BDay! Memorable...
Otherwise, perhaps maybe think about Boma? AKL is beautiful and exotic like the Polynesian, just different theming and there would be something for everyone on the buffet and they do a nice job of celebrating special occasions.
I have to say, it's really hard to find a true comparable comparison to replace 'Ohana, I'm trying to plan that myself.
Good Luck with what you decide!