I've made several pairs of convertible mittens. I never put buttons on any of them. The flaps pretty much stay flat with no problems. We didn't want to do velcro because everything sticks to it. I say make yourself a pair of those Ravelry mittens. Use the best yarn in your favorite colors and treat yourself. Once you make and wear these mittens, you get spoiled really fast. They're fabulous driving gloves.
Welsh corgis are cool.