Now, we can also have a TMP-style "rec deck," and some form of sports facility, and that would pretty much cover all four, and all four make perfect sense for a ship the size and complement of Enterprise.
I'd still keep the "TMP style rec deck" where Probert wanted it, right behind the bridge at the ship centerline. After all, "LTBYLB" claims that it is three decks high, not two! Plus, such a location would serve the "LTBYLB" plotline well, as our two clowns with their ability to remotely shut down turbolifts would then be hiking down stairwells directly below the bridge, running around the center of the saucer in search of the next well down. (Little would they realize that they could use the multi-deck Rec Room as a shortcut!)
Since that one is explicitly Rec Room 3, yet in "Charlie X" we hear of Rec Room 6, we should probably not limit ourselves to thinking in terms of just four rooms! Let's assign the four saucer rim squares to, say, Rec Rooms 1, 2, 4 and 5 because there is no conflicting info on those, and then place Rec Room 6 on the forward part of Deck 3 because we know its deck from "Charlie X" - and Rec Room 3 on the aft part, going down three decks to reach Deck 5 of both "LTBYLB" and "Trials and Tribble-ations" fame.
If we desire, we can then add a ceiling window rectangle to Room 3, too - it just happens to be shuttered by that yellow thing that's so prominent on the aft bridge superstructure of the TOS ship!