DixieRose,
You describe exactly the same experience that I have had. Finally decided that we could cross these perennials off our list.
Someone on the Perennials Forum posted the following on-line nursery which is reputable. Have you found it? This appears to be an excellent source of plants for our area. Check out the tender perennials section of the catalog. www.lazyssfarm.com

I just wanted to say that I have two different types of heuchera growing in my yard, Velvet Knight(have 2 plants) and Green Spice (1 plant). The Velvet Knight will be 3 years old this spring and it has grown larger every year. I bought Green Spice last spring and it too is a little larger than last year. Hopefully, it will take off this year. None of my plants die back in the winter. In fact, all 3 look exceptionally healthy right now in February. I have very alkaline soil, which they like and you aren't suppose to fertilize them. Do you think maybe your soil is acidic or did you pamper them too much? I read on one website that you should dig them up every year and plant them deeper because as they get bigger, the stems end up out of the ground. I haven't done that, but I have added mulch to them, so maybe that helps keep them covered. Mine also get a pretty good amount of sun. I would say at least 5 hours of sun.

I plan to try some heucherellas this year.

Hope that helps,
Rae