What kind of All Inclusives do you think your non-divers are looking for? And what non-diving aspects of Cozumel did you manage to sell them on? It might make a difference in what gets recommended. I haven't done any Coz AIs, but we have stayed in a number of places and also used Hotel Cozumel just as a place to sleep. I wouldn't give it a blanket thumbs-up--especially if the travelers are not super low-maintenance.
While its proximity to town is great, there are quite a few resorts that will have prettier beaches (Hotel Cozumel has a very decent fake-a-beach setup) and, I'm guessing, nicer rooms (our room was comfortable, but also small and spartan without much decor--we talked to some fellow divers in a "deluxe" ocean view who also said their rooms were bare-bones in looks). And the property is on the inland side of the road, so only a few rooms have anything approaching an ocean view. It is, however, fairly cheap, with nice-enough public areas. And if you want to learn the "gangnam-style" video dance moves next to the pool, or are amused by listening to a bunch of people (cruisers?) get a loud, peppy "Mexican food and drink" lesson, it might be your place. There are plenty of resort activities, a tour desk, etc. They also have those underwater air-helmet scooters onsite--they don't go very far, but they attracted a fair amount of non-divers who appeared to enjoy looking at a few colorful fish eye-to-eye, and the scuba guys who were shepherding them along found little underwater things to show them and pass around, plus take pictures. It's sort of fun to watch, because the people doing it look to be very happy, and their heads look like little baseballs thanks to the curvature of the helmets.
And for all I know, the food might be great--we didn't eat a thing there. But if you're looking for something a little more upscale, you might want to look farther afield. Or you might love it if you're just looking for your basic needs to met with economy and convenience.
For us, location means a lot in Cozumel. We used to stay at La Ceiba, which now also has an AI option. The grounds look pretty nice these days, but it's really, really close to the cruise ships. For some, that's a plus. For some, including us, a minus.
From the street, the Palace has always looked good and has a great, close-to-town location. As long as your friends won't be diving, I'd also look at a few places north of town (are any AI? That I don't know). My experiences in that direction are limited, but it strikes me as quieter and overall maybe a bit prettier.