Take a panga (skiff) to Playa del Amor and see El Arco at the same time. Laze for a while or snorkel, then head back for grub or a margarita. Get tipsy on a gorgeous sunset tour and then finish the job at a wild club. The next day choose between quiet shopping at San José del Cabo or something active: surfing at Los Cerritos or diving at Cabo Pulmo.
Four days gives you all of the above. Or you could rent yourself some wheels and do a loop of the southern cape. Start heading east, through San José del Cabo, and take in the awesome scenery of the eastern cape, one of Baja’s best unbeaten paths. Stay in Cabo Pulmo for snorkeling and diving, then cruise north on day two to La Paz. Hikers will want to see the Sierra de la Laguna. Spend day three in the chi-chi galleries and great restaurants of Todos Santos or surfing. Head back to Cabo San Lucas on day four and end with a fancy meal at Sur or a relaxing sunset tour.