I wear mine outside my boots. Many of the locations I ride, I'm riding through brush and trees and I'm not terribly interested in having a stick or a leaf or a spider brush off down inside my boot LOL. Plus, if I have to get off and walk to open a gate or fix fence, I would end up with all manner of grass seeds and burrs down inside my boots.
FWIW, I have found out that if I buy a pair of pants that is too short, they will ride up and twist around my leg. If I go with a 34" inseam or shorter, they will ride up no matter what I do, but I can wear a 36" inseam and not have a single issue at all with them riding up or twisting around.