i grew up on hartwell, i like the fact that the little lady and i can get lots of privacy on that lake
plenty of coves to pull in and beach/drop anchor.
My parents now have a weekend home on hartwelll (seneca river). Their neighbor keeps a Cal 25 in the same cove.
While it has the same issues with unpredictable winds i find just the seneca river area has maybe 5x more area between bridges than all of Saluda lake. At the big water there is generally good wind and waves (where portman marina and western carolina sailboat club are) as its such an open area. There is however 3x more water traffic than anywhere else.
And generally good "sailing" weather differs from what all the PWC's and motorboaters consider good weather. I'll take a cool windy day of sailing over a hot day where i have to motor any day. Boaters can be a PITA but generally early spring/late fall offer better winds for sailing and about the only others out there are going to be the fishermen. They are either trolling or in the coves so they are out of my way.
IMHO there is no perfect lake in the upstate for sailing, there will always be issues with tree cover, lack of open water and too many peaks/valleys for good predictable winds. But its home and I'll make the best out of the sport i love.
For days with no wind we also have motorboats and jetskis...but to me the perfect day is day on the sailboat...not to hot...not too cold...just on the boat with no one around. Wind or no wind...it's not really cruising if you have to be anywhere at a specific time.