Unfortunately not one hotel in the area has a slide.
I know there's several non-Disney hotels and resorts in Orlando that have great pool slides, but for some reason pool slides are hard to come by anywhere in Southern California.
I think there's a few places in San Diego and Carlsbad that have pool slides. The Lawrence Welk Resort is the only one I can think of off the top of my head, but I think there's one to two more.