In the summer of 2009, I was asked to find a convention center at which to hold a meet-up for my job. Without hesitation, I chose the Connecticut Convention Center. There is a hotel adjacent to the center, so if anyone is coming from out of town, it's very easy to find them a place to stay for the duration of the meeting. The convention center is intended to hold very large groups of people, but it is also possible to simply rent out one of the rooms they offer, which is what I did. The room was very well kept and neat when I entered it, and the staff was very helpful when I needed to locate a podium and set up chairs. Our meeting lasted about two hours and there were no distracting noises from outside the room, no interruptions, etc. It was a very professional environment that I would not hesitate to use again. My only complaint would be the accessibility issue - if someone is in a wheelchair, there could be a problem as the elevators were out of order both when I went to scope out the place and when I actually had to hold the meeting there. Calling ahead can make sure there are no snags in the accessibility department, and judging by the staff's reaction to me when I was there, I'm sure they would have no problem helping to accommodate you wherever possible. Definitely make sure you check out the room you're planning to use ahead of time though, to make sure you get what you want. Overall, my experience was a great one.
I've been to several conventions at the Connecticut Convention Center in Hartford. It's right in downtown Hartford, and is extremely easy to access by car, train, or walking. Because the center opened in 2005, it's relatively new. It is spacious- over 140,000 square feet of exhibition space is available in addition to a ballroom that offers 40,000 square feet and another 25,000 square feet of other space. The Convention Center also offers catering, which can be very helpful to event planners. Most recently, I visited the center for an education and technology conference. It was helpful to be able to access my laptop using their free wifi capability.