What I saw this summer was a definite increase in users that I associate with the extension to east bath house. Pretty much all those were adults who can ride the 11 mile RT from Cedar Creek, so any families I saw I assumed started at CC and headed south.
But I wasn't parked at Lot 5 doing a survey, so don't really know.
I can see a family parking in Lot 5 then going to the beach, grabbing some hot-dogs then hoping on the bikes for a run down towards Tobay, with ice-cream after. 7 miles RT might be an OK distance and it does give options to either ride east and back or north and back. I think the $8 charge to park a car to take your 2 or 3 kids on a protected bike ride is something parents will not have a problem with, it's cheap for an activity with kids. Recall as well that Nassau County is requiring county activity passes and charges a parking fee to use Cedar Creek on weekends, so no different then going to JB. I've no clue if they allow or charge more for non-county resident at CC.