Teaching an "all done" command shouldn't be all that difficult. Work on engaging your dog with the tug (or throwing a ball, doesn't matter what the game is), having him release the toy on cue several times during the session, and then starting the game again. It would look like this: Tug, tug, tug, "out" (the dog drops the toy), "yes!" (the marker for the release - continuation of play is the reward), then tug, tug, tug some more. Rinse, repeat.
When you're done, pick a cue to signal that the play session is over, then put the toy away and walk off, ignoring the dog if he pesters you to continue. Be consistent, work on it a few times a day, and eventually he'll learn that once you've used that cue and put the toy away there's no point in trying to get you to come back and play some more.
When my dogs were getting too rowdy in the house and I wanted them to stop, I'd cue them to come to me for some simple obedience exercises, such as a "down" with eye contact, and I'd reinforce that with treats for compliance. You could use going to a mat if you prefer, or even just a sit. Once your dogs will stop what they're doing to work with you, you can put it on cue.