I was in the Israeli Army for 2 months and have adopted a really simple and quick way they use. You just get a rubber band, and tuck your pants underneath the rubber band. The rubber band just sits over your socks -- and once you get to your destination, you... well I just untuck the pants and keep the rubber band on all day.
I use those flat rubber bands, they never seem to untuck, and they are wide so it doesn't feel too tight on your leg. It works really well... tucking into socks I've tried and depending on which socks you have the pants tend to untuck and it gets stuffy under the sock.