I personally set mine up on two 4 x 4 post (freebees from work) with cinder blocks under them, I can get for or five hives on them and do not look all that bad. I will be making some 3" pipe stands (again free pipe from work) in the very near future and concrete them into the ground, these will be 21' long and can hold several hives.
I know you asked for suggestions other than cinder blocks, I have seen just about any and everything to sit a stand of bees on, most times it was what ever was handy and cheap. Are you looking for something that looks good, just more sturdy than cinder blocks, one hive or multiple hives, etc, etc. Are you going to fabricate them yourself out of wood, metal, plastic, concrete, etc, etc.
Never tried milk crates before, but think into the future, say this summer when you have three, four, five, six supers all stacked up and full of honey. That is a lot of weight to support on a plastic milk crate. Now that it is top heavy with honey and a big gust of wind comes along, neighbors nosey dog, skunk, etc. for you to find a busted up hive the next day spread out on the ground that took a tumble is pretty humbling.
Most commercial beekeepers use pallets that are made to their specifications to hold hives and they even have metalclips to hold them in place for transport. Think of a tractor trailer load of hives loaded with a fork truck.
I am a faithful user of screened bottom boards. That means that your hive stand needs to allow the mites to fall out of the hive. Visit the http://www.beehacker.com/wp/?page_id=22 site for various hive stand designs.
I place an old tire on the ground, then put a display(small) pallet on top.This gets them up off the wet ground far enough or me to work at easily and is recycling unused stuff that would otherwise just clutter the yard.