LindaSchipper ....Have you considered fleece? I've used it for all of my design walls. Tried the plastic/flannel tablecloths, felt and flannel before concluding fleece was the best, Plus it would give you a bit of a stretch when putting on your frame. Have never regretted the fleece.
OneByOne mentioned grey as a possibility. I have preferred black after seeing many white/cream walls that look filthy with time. Maybe they aren't, but they sure look so. The black fleece wipes threads off easily with a lint brush. I have at times put on chalk lines to help with layouts.
I don't want to be Negative Nelly here, but like many others have already said, I see a lot of questions that may mean the result may not be as positive as you are optimistically looking towards. It could mean a lot of $$$$ spent without giving you that return on investment for happy sewing that you want! I hope we are all wrong.
Good Luck with your project!