I use
lens wipes that I bought from Costco. They are a soft material (unlike the ones I bought at Target, which are more paper-like) and I like them a lot.
After I clean my glasses, if I'm not near one of my kids, I'll clean whatever touchscreen is closest to me at that moment -- my phone, my tablet, the screen in my car. I haven't taken one out specifically for cleaning a screen, but I seem to always be near one that needs it when I have one in hand. We seem to be able to get quite a lot of use out of each sheet!