^^^^^as mentioned, Califon would be a nice place to stop for lunch.
If you get to the train station and cross academy street and come right to the left side of the large firehouse you can make a right there on the next street and about 200' up on the left will be Rambo's country store. No uphill to ride up with kids with this option, and much closer to the trail.
Rambo's has a deli and $0.25 ice creams for the kids. Thats no typo.
High Bridge parking to Long Valley center is roughly 11 miles each way.
The columbia trail from the center of long valley from middle valley rd on a nice weekend will have about three hundred thousand people on it.
LV center has four pizzerias, Dunkin Donuts, Baskin Robins, delis, Chinese, Thai, Brew Pub, etc.
CycleCraft is right in the middle of Long Valley to tune or fix pesky bikes/pick up a spare tube, etc.
As far as singletrack to dip off, Nassau trails in high bridge, one short section on the south side of the CT right by the large bridge in the gorge that parallels the CT for about 200', and after you pass thru LV on the right before Frasier steel theres some if you know where to look.
bunch around the Gillette trail intersection and SchooleysMtn Park if you dont mind some climbing. Thats it. of those, Nassau trails are by far your best bet.
Have fun!