We usually try to stuff everything into carry-ons, but I screwed up when booking our Feb trip. One of our flights was basic economy on AA. We were not allowed to have carry-ons or access to the overhead bins, so we were forced to check a bag. Luckily I noticed before we left for the airport, as we would have had to pay $50 to check both carry-ons and an additional $25 per bag had we taken our carry-ons to the gate and been forced to check them there.
We're probably checking 3 bags this trip...we're going on Sun Country (direct from MSP) and they now charge for every carry-on, and it's actually cheaper to check a bag!