News flash! I checked the rates for the Motel 6 and the Desert Inn for dates from February 1 - 5. For 2 adults, the Motel 6 is $50.39 a night for a special "Click 6" online rate. The Desert Inn is $79 a night. The Quality Inn for a room with two double beds is $60.34 a night with a AAA discount. I don't think your son will share a bed, but you can save $9 if you want to.
I'd say go for the Motel 6. You might have to walk a few extra steps, but it's probably the better "economy" place in the area.