Yep that's exactly what I've been doing with SW for years. I agree with all that you've said. We have to go to Asia at least every couple years so we will just buy cheap bags for that because quite often one of them will get absolutely destroyed on the trip. Domestic flights we generally will not check bags at all if we can avoid it. Vegas trips I can do with one backpack, but my wife is of course more challenged than me by this policy.