We always stay at the Riverside RV Park, next to the Interstate, on the Colorado River. Actually in Winterhaven CA, a couple of miles West of Yuma. An older park, nice pool etc. Easy access to freeway, long berm between fwy and park, great for walking your dog. Sites both under trees and in open. Quick run to Algodones MX, where we have been getting our dental work done for years.
Yuma has a nice mall, Yuma Palms. All the usual chain stores and restaraunts, nice movie theater. Big covered swap meet on weekends. Contact Chamber of Commerce for more info. Time zone in Winterhaven is different than Yuma, be careful.