JesseInCT said: Another idea you might consider with large pots is to not fill them completely with soil. I've seen others here suggest putting plastic milk cartons in them first and then adding soil to the top since you don't need 12"+ inches of soil for semps and sedum. Makes the planters much lighter and more movable. 
Those cement planters are going NOWHERE because they are probably more than 120 pounds a piece. I made them heavier still by adding back the sharp black rocks the previous owners had in the bottom! Milk jugs sound much easier and a way to keep plastic out of the landfill!
Just how deep does the soil need to be? I put probably three times as much soil in those planters than is probably necessary.
I also completely destroyed a planter trying to drill a hole in it before successfully drilling three others. My first reaction was dismay followed closely by, "hey--crevice planter!".
