The following is a compilation from a number of posts over the last few years.
Pete Johnson
In the Sound, the vis thing you just get used to and start seeing with your hands.
CT Shore diving is limited do to water access, not a lot, and that the Sound is shallow on the north side especially west of New Haven with a mud/silt bottom. You can be a mile out and still need to look out for oyster stakes (less then 30'). Most go out to RI or up to Cape Ann or Maine for the visibility and bottom structure.
Try the boat ramp at Pleasure Beach in Waterford. Good parking and an easy after work and night dive
New England Diving of CT is in Wallingford and is a full gas Tech dive shop. Paul & Pat are good people.
New England Wallingford Connecticut CT Scuba Diving Center Dive Classes Lessons
SCUBA Shack in Rock Hill is just south of Hartford is the only GUE/DIR shop in the Northeast.
Scuba Shack - GUE & PADI Training, Diver Equipment - Connecticut
Besides the Brownstone Quary, in Long Island Sound there are 3 charter boats out of the CT side. Atlantis in New London, Orbit in Bridgeport, and Captain Sam down Norwalk/Stamford way. In the Sound expect 5-15' vis with winter temps in the 30's and late summer vis can be 2' and less with temps around 70. I use a 1/4" farmer john in the summer and a dry suit for the other 9 months.
Most go out to Rhode Island and hit the wrecks around Block Island - Submarines there are the Greman U-boat U-853, USS Bass, USS L-8, and way south in 250/275' is USS Spikefish. All of the USS boats were sunk as targets. Other wrecks are the Black Point (victom of U-853) the Idean, Larchmont, Lake Crystal, Lake Hemlock (in the Sound), Mary Arnold. etc.
Pick up Gerry Gentiles books on "Shipwrecks of Rhode Island and Connecticut" and "SHIPWRECKS OF MASSACHUSETTS: SOUTH." He is currently researching a book on Northern Mass.
Gary Gentile Wreck Diving
All the dive shops have some typr of club and there are a few independent clubs around. If you are mostly into travel the Innerspace Club in Manchester may be a good one for you.
Here is a general web site that is what I think you are looking for.
Hunting New England Shipwrecks