Key West Day-Trip is a real time commitment — fit it in only if it's a priority.
Allow Full long day (12+ hrs).
The drive itself is the attraction — the Seven Mile Bridge and turquoise straits are unforgettable, and Key West has Hemingway's house, Mallory Square sunsets, and Duval Street's party. The catch: it's ~3.5 hours each way, so a day-trip means most of your day in the car and only a few hours there — it really wants an overnight.