We bought our Jacuzzi under a medical emergency situation. Didn't have time to shop around and don't recognize the names of the better spas you guys are talking about. But in case it helps anyone, our spa had just that stupid spray on insulation on the bottom. We live in Ohio, and the electric bill skyrocketed. My husband opened up the cedar base and stuffed the bottom full of insulation, 0 the basic pink fiberglas stuff you put in your attic and walls - in addition to setting the whole thing on insulating foam.
My electric bill initially shot up $75 a month. After we insulated the tub, the electric bill increase turned out to be aboutn $15 a month - winter only. We don't use it in the summer.