Let's meet near Watertown Square and walk the Charles River Path. After the walk, we can walk over to Not Your Average Joie's in Watertown Square and do some eating, drinking and socializing.
Watertown Square is easy to get to by bus, car, foot, etc. There's plenty of parking in the municipal lots.
We can meet at the entrance of the DRC's Dealtry Pool. It has a parking lot - just look for the "swimming pool" sign off of Pleasant Street. We can walk all the way to Moody St and back (about 7 miles) or take a shorter walk, depending on the group. There's lots of nature and history along the way, and places to stop and admire the beauty of the river. There are lots of bridges where we can cross the river and come back on the other side.
We usually cover about three miles of trail each night in a bit over an hour.