I've always enjoyed the Pumpelly trail, It's 9 miles out and back if you're up for a longer hike. Parking is free as well, but you do have to park along the side of the road.

A fun loop is Birchtoft/Spellman/Red Spot if you're comfortable with a little bit of easy scrambling - Spellman is pretty steep and rocky. Very quiet when I did it, but parking was not free. You might be able to park at a lot outside the pay area if it is open though.