25-30 guests would be ideal. But I agree, I don't see them doing this any time soon.
Regarding food, my preference would be both quantity and quality. I don't mind a meal or two on our own, but it seems like the meals on your own have been going too far in the other direction. In Greece there were a ton, and I hated having to figure out where we were going to eat all the time. That's one of the reasons I go with a tour company.
Nat Geo covered all the meals except for one dinner, and the food was excellent. Calfan can jog my memory, but I remember one so-so meal in our first guest house. There wasn't much else around though so I don't think they had much to choose from. I can't wait for the Peking Duck!!! All four of us are looking forward to trying it.
More pre-planning would be so easy for them to do. Nat Geo has most of it on their website. They send out a trip specific link after you sign up, and there's tons of information about the trips, cities, currency, what to pack, etc. And if you have any questions, there's your specific person to contact. I can't remember when the box came, but I think it was a month or two out. It had a hat, water bottle, gear bag, luggage tags, book about where we were going, maps, etc. Very nice.