I've used pre-quilted solids (by Springs) to make appliance covers. And - this is just my experience - I was not pleased. The threads that are used to do the quilting are slippery, and so they worked their way out of the seams; with successive laundrings there were a lot of loose threads. You can do a teeny-tiny straight stitch along all the cut ends, which will help to hold the quilting threads down. But it's extra work.
I'd be interested to know if other people have had this problem and if so, what they did.