The South Shore suburb of Weymouth doesn't have a ton of open space, but what it has is really quite scenic, including some real hidden gems such as Pond Meadow (which it shares with Braintree) and Webb Memorial State Park. I visited the latter spot over the weekend and was pleasantly surprised by its pastoral feel and occasional stunning views. It isn't a huge open area, but there are enough trails to make for a leisurely morning or afternoon walk and the place is made for frequent stops with its benches, grassy areas, and outlooks. From certain parts of Webb Memorial Park, you can see the Boston skyline, sections of Hull and Quincy, and some of the islands in Boston Harbor, including Grape Island, which seems almost close enough to touch. The low hills and lowland areas make Webb Park feel a bit like a smaller version of World's End, a spectacular conservation area just to the east that is popular with hikers.
Several pictures of Webb Memorial State Park are shown below:
A group of 25 of us went on a long hike through Hale Reservation in Westwood (and briefly crossed over into the Noanet Woodlands in Dover) a little more than a week ago. Hale is a huge reservation, so we went at a brisk pace from the start, looping northwest from the Cat Rock parking area over to the pristine Storrow Pond (see photo) near the northern edge of the reservation. After spending some time enjoying the sights of the pond and the sounds of the stream that fell away from it, we turned southwest, hiking through some of the most remote-feeling land in the Boston area along a part of the Storrow Pond Trail. 
After nearly a mile of walking through some very deep woods, we approached Powissett Pond (see photo), which is in the hilly western part of Hale Reservation. Like Storrow Pond, Powissett Pond is a small but scenic body of water, and we spent some time on the picnic tables there relaxing and wandering around the beach area. From there, we started climbing west toward the southwestern edge of the reservation, staying mostly on a fire lane trail, but eventually veering off to reach the highest point of the hike.
After several fairly steep twists and turns along some minor trails, we made it to the top of Powissett Peak, which is about 400 feet above sea level and has some sweeping views to the west (see photo). It was a bit windy at the top, so we didn't stay long, backtracking to the fire lane and dipping down into the Noanet Woodlands where we had lunch. From there, we took some little-used trails east back into Hale, skirting Strawberry Hill and ending up back near Powissett Pond. From there, it was an easy (and scenic) walk back to the parking area via a trail that went alongside Noanet Pond, the biggest body of water in the reservation.