My husband just got our computer up & running again after 4 days of being "down". I work part-time at a nursing home as an RN supervisor which I really enjoy. A good size for a lap quilt is 40"x 60". As older folks tend to stay cold, using a thicker batting is okay. Tying the quilts is fine. However, I do discourage putting actual ties on the quilts to hold the quilts on to the wheelchairs. By law, that would be considered a restraint, therefore rendering the quilt useless to be allowed as a cover. Just wanted to pass that caution on to you. Your heart is in the right place; bless you for wanting to do this. Also remember the lap quilt will need to be washed frequently. I wish you the best on this venture!