Thanks for the ideas, everybody. Covana is very nice but I need to be able to see open sky.
As for ultrapoolandspa, thanks for posting this site! I had checked out the Ultralift, but learned that the max corner radius was 16, where my spa is 17, so that is a no-go, HOWEVER, the Boomerang on their site was recommended and I'm very intrigued by that as I'm told it does the maximum work possible in lifting the cover and is fine with 17 inches radius. I hope they will confirm that in writing before I order. If not, I'll be back here begging for help again. : -)