Downtown TJ (Avenida Revolution) is good for an afternoon, maybe an evening if you like loud discos. La Zona is good for as long as your stamina holds out. Las Playas (beaches) de Tijuana are close by. Rosarito and the other points along the coast all the way to Ensenada offer breath-taking views and beautiful beaches. The tourists have all been scared off by some well-publicized recent events. This creates an opportunity for others. I'm sure you will be given the red-carpet treatment if you decide to visit.
Enjoy your visit!
Enjoy your visit!