As stated previously...for dinner, bus to MK (leave plenty of time...at least 90 mins) then either boat or monorail over to the GF. For breakfast? I would actually use a cab. I've had a few very close calls using the buses. I was late (about 15/20 mins) from 'Ohana breakfast when coming from AoA. And for my GF dinner (1900 Park Fare) I was 20 mins late from AoA!! I know how long it should take and have never been late, always early, until my late May/early June stay. It was very disturbing..it just shouldn't take more than 90 mins to get anywhere. If you end of waiting even 30 mins for a park bus to come, it shouldn't take more than 20 mins to get to any park. Then, to get from MK to the GF or Polynesian should not take over 20 mins. But, that's exactly what happened to me.
If your 'Ohana ADR is going to be before 9am? I would take a cab just to be sure and not have to spend a huge amount of time.
Yeah, I said that...I know you all are so used to me saying the transportation system works fine, but then, it didn't. I am becoming a rental car convert!!!