I've stayed at the W several times for work and found the staff friendly and rooms large (esp. compared to other city Ws), but it's definitely a city location (convenient to Gaslamp District, PetCo Park) rather than beach. Torrey Pines is La Jolla, nicest family beaches are probably in Coronado or Encinitas (Moonlight Beach)...to hit all of these, I assume you'll have a rental car, so I'd probably just go with the best deal via Kayak/Expedia. AirBnB might be an option, too, esp. if you're willing to go further north than the city proper.