My favorite is off recreation road....not the main entrance. Ride mountain trail to woronoco to the new trail called split rock to shaw trail. Then take the south ridge trail toward the pond.. Cross the dirt road and hop on boulder trail..climb back up to fire road and then look for a right for north mountain by pass. Ride the bypass all the way back to north mountain trail back to recreation road. Should be about 14 or 15 miles. Good luck.
Get out and ride even when you don't want to because ten minutes into the ride you'll be glad you did.
I rode at Pawtuckaway for the first time yesterday. There's definitely some good stuff there. A little more doubletrack than I'd normally ride, but it was still fun and entertaining. The one thing I was really surprised about was how scenic the place is. Some amazing pond-side vistas and crazy glacial rock formations with the trail looping around them. We did the loop mentioned above- definitely well recommended, although the wet rock gremlins were out in full force yesterday.
Split Rock is fun but you can miss a lot of good stuff on lower Shaw and Woronoco. A good option is go down Shaw, do Split Rock out and back, then continue down Shaw to Fundy and all of Woronoco. Climbing Shaw is not as much fun as going down! A trip up to the firetower is worth it very once in awhile - definitely some HAB.