Gloucester for flounder
I grew up in Gloucester and can give you three suggestions from shore. If I were to go today, I'd try the rocky point on the West side of the harbor(looking out from the Boulevard.
Park in Stage Fort Park and walk through the old fort to the point. The second spot woult be the inside of the breakwater on Eastern Point. The third would be from the boulevard between the bridge and fisherman's monument.
From now on you should be able to pick up some Winter Flounder in either spot. Maybe not a lot, because their stocks are just starting to come back in the GOM, but some. Best bait, by far are Sea Worms.
Please let us know how you do.