A little late for your schedule, but over the last 4 years I have spent a week or two at Imperial Dam, and the rest of the winter at the Quartzsite LTVAs (usually La Posa West). Quartzsite has a bunch of restaurants, activities, junk booths, and, of course, the big tent show in mid January.
I agree that there isn't a lot to do at Imperial Dam, but that is one of its perks. I spend time reading & relaxing. They have a great library. Morning exercise activities at the gravel pit pavilion, as well as Sunday afternoon music jams. About 25 miles to Yuma for shopping.
Since the same LTVA permit can be used at any of the LTVAs, moving between them is a great option.