Legoland is more pleasant for walks with small kid vs seaworld which is rather crowded and cold for splashing activities in dec/jan. Westin sheraton and some sort of hilton are attached to legoland with private entrance. You will likely need a car to get around unless you stay in downtown (with all pros and cons) plus car will allow some nice coastal drives in tbe area.
Some la jolla hotels (es, marriott etc) are close to shopping center and food options - sort of urban area but morw manicured and not as busy as dt san diego...