Abstracta
Abstracta sits at 624 Duval, in the middle of the street's gallery and shopping stretch, and it has been there since around 2011. The stock runs eclectic and deliberately offbeat rather than the island-scene paintings and sunset prints that dominate a lot of Duval, and among the things people single out is sculpture assembled from reclaimed metal, which is a more interesting object to carry home than a framed print.
The practical advantage here is the hours. Most Key West galleries close in the late afternoon, and Abstracta stays open into the evening, so it fits into the part of the day when Duval is actually at its busiest and you have nothing else to do but walk the street.