36 to 38 foot boat for The Keys?
The Tartan 37 is a very nice boat, but I believe its PHRF is around 177 and thus quite slow. They are not especially spacious down below and have just a qtr berth. Not sure about its offshore performance, though certainly someone here does take theirs out there. Also, Tartans have cored hulls and an older boat could have undetectable problems that would be expensive to repair.
Given your special criteria, $90k budget and desire for a real sea boat with excellent accomodations, I would suggest looking at the Wauquiez Hood 38 - Mark I. You may be able to find a Mark I model (Baltic/swan style companionway) for $90k. These are Ted Hood designed, solidly built boats that are excellent sailors. They are keel/CB designs with a draft of 4''6". Best of all, they are luxurious down below. Truly exceptional accomodations with a private stateroom forward and private aft qtr cabin (which makes a great sea berth). The joinery is beautiful and with a 50% ballast ratio, they are very stable. PHRF of 129. This is the sistership to the Bristol 38.8 and Little Harbor Hood 38.
I got one a few months ago and am just thrilled at the quality of the build and performance of the boat.
Hope this helps.