Gary,
I live in the area so I'll give you an honest review.
Seaboard is an old marina without many upgrades. There is a lot of very shallow water in the area. It has a reputation for some heavy duty partying, especially on weekends. You will not be able to get to Glastonbury center or to Hartford without a car. In fact, from Seaboard, you can't get anywhere without a car.
Hartford has lots of restaurants, museums, etc. and can be a fun place to visit but it is woefully lacking in transient dockage. There are some places to tie up in East Hartford (across the river from Hartford) but getting a ride (or a cab) will be necessary.
On your way up the river (and it is a beautiful river to cruise), consider Middletown. It's 33 miles from Old Saybrook and there is a town dock (wharf) that you can use, although weekends are busy. It's a short walk to the downtown, which has numerous restaurants and a very active Main Street.
If Middletown is crowded, consider one of the three marinas across the Connecticut river in Portland. Virtually no one this far up river answers a VHF radio call but you can simply pull up in front of their docks and ask for a place to tie up. You won't be turned away.
At any of the marinas in Portland, you can just ask a dock mate for a ride to Middletown or if you have a dink, take it across the river. If you have kids, Portland has a water park that they will never forget.
As I'm sure you know, the Connecticut River is pretty easy to navigate. If you decide to visit the upper river, follow your charts (or GPS chartplotter) carefully when you approach Middletown. You will make a big left turn at Bodkin Rock and after that, stay absolutely in the channel, which is to your port side. The river is wide here and some have a tendency to run down the middle. Not a good idea as there are obstructions there.
I hope you visit next summer and have a successful cruise.
Bill
