I went through this same ordeal last summer.

What area of Connecticut do you live in? There are certain areas (Fairfield county, certain suburbs of Hartford, etc) where you'll basically be charged more just because they are presumed to be affluent areas. Not fair but true.

What sort of analysis did the contractors do to come up with that price? Did they inspect your attic and decide that they need to replace all the sheathing and/or structural members? Are they trying to solve a particular problem that you've had, such as ice dams? Are they tearing off multiple layers of shingles and assume they'll have to do some work to fill the resultant gaps in your siding?

Are you getting new gutters? Some roofers automatically include them whether you need it or not because it's an easy item to mark up.

Are you on a busy street with no parking available for a truck or dumpster? If they have to cart stuff away by hand, they'll charge you for extra labor.

As a data point, I paid $15,000 for my roof which has three distinct sections and included removing 2 layers, solving a ventilation problem (had two solar fans installed), and a ton of attic insulation. So unless you live in Greenwich or something, I have to believe the $18,000 quote is too high. $14,000 could be reasonable depending on exactly on what they're doing.

If I were you, I would try to get a few more quotes. In my experience the larger companies are the most expensive as they have larger overheads they need to cover. If they do windows and siding, then you have to compete with all the other jobs they could be doing instead of yours. Smaller companies that specialize in roofs might give you a better price. I selected a medium-sized roofing company and while I feel that the price could have been $1,000 less, the job was done in 1 day about 2 weeks after I signed the contract and I only had to pay 25% in advance; the balance was due after the job was completed to my satisfaction.