I can truly call this Marriott my "home away from home". I travel for business and have stayed at a few other hotel chains in the Del Mar area. I found this Marriott and have not changed hotels since. The rooms are contemporary and very comfortable. For the rooms I have stayed in, they had a mini-frig and the alarm clocks have an iphone 4s and below adapter in case you forget your iphone charger. The gym is decent and workable. If you like to run, I recommend the Torrey Pines beach area.
As others have mentioned, their focus on customer service is what sets this Marriott apart from their piers. The daytime front desk crew of Jerry, Lydia, Kelly, Sisily, and the Nicole's are top notch. They're warm, friendly, and get you checked in and on your way. When you are in your room and need to visit the concierge lounge, an equally top notch staff awaits to greet you. Sarah, Stephanie, and Grace are all very gracious and helpful; making my stay as pleasant as can be when your travelling and away from home.
Though I am writing this review from a business travelers perspective, I have seen a lot of families stay there on vacation. I plan to do the same when I am vacationing in San Diego.