After some research, we decided to eat at Santiago's Bodega last night. It proved to be an excellent choice for what we would describe as "small plates" rather than simply tapas.
We made reservations for 5:00 p.m., which allowed us to arrive partway through Happy Hour, which features about three small plates, mussels, beef empanadas, and beef skewers, at half price, and wine or beer two-for-one.
The menu is extensive, and we probably shared at least one more dish than we thought we would, a delicious bread pudding from the dessert menu.
Although food quality is of the highest priority, we should add that the atmosphere is lovely and the service was friendly and generally terrific. Thank you, Alan!
In the event our travels ever take us back to Key West, Santiago's Bodega will be a definite stop.