My typical carry-on configuration is the backpack where I stow my laptop, plus a purse and a cloth bag of "stuff"- books, food, etc. Of course, I have to consolidate that into 2 items to carry on. The laptop and cloth bag go under the seat in front of me, the empty backpack goes overhead, and if there's not enough room under the seat, my purse gets tucked behind my legs during take-off. No F/A has ever made me stow it. When I retrieve my laptop, the purse goes in the under-seat area.
Don't you just LOVE Coach-class calisthenics?