i never had luck with tablecloths. i finally broke down and *bought* pure white 54" flannel, enough to cover a 12' across and 8' tall wall in my freezing basement ( i use a heater).
i stapled it right to the wallboard straight across from one side to the other, i can see a whole quilt at one time. believe it or not, it was cheaper than buying a white flat king-sized sheet. got it at joann's with a 50% coupon. 7 yards.

That is exactly what I am thinking of doing! I thought I saw this some where, but could never find it again on the internet. I seem to remember that they sewed along the outside edges to secure the flannel. Have you got any ideas on securing the flannel?

i use a large piece of solid colored cheap fleece that I had laying around - it's just tacked up on my wall. Fabric sticks and I can easily pin to it if necessary.

So flannel, fleece, batting or felt all work equally well, it sounds like. Fleece on sale at Joanns this week

I used felt from Joann's.