Yeah I see your point. What I would propose, though, is not about breaking focus really. I'd prob wait till everything was done.On OW checkout dives anywhere, it's temping to break focus and let diver's go play. But I understand it's like dangling a treat and not letting them experience it. With all levels of certification dives (AOW, Cave, RB, Rescue, DM, etc) It's still best to just complete the certification and then go play later or re-visit the site.
In the pool for their class, after all the requisite stuff was complete the last day, they did a little play time session. Everyone swam a few laps, swimming through hula hoops, then freetime playing with some toys, just going around getting used to bouyancy shifts, etc.. I thought it was a very good use of time.
At Blue Gratto, I would have proposed that at the end of the day, after everything was done, they could do a little follow-me session. Drop down to the 30ft platform, maybe a circuit around the place for a look into the "cavern" from just outside it, ascend up to the dive bell for a look and opportunity to pop their heads in.... just a quick tour. The place outside the cavern really isn't very big but they didn't even get to see it!