Al, I haven't set one up as storage (yet), but have unloaded thousands of them over the years. Very durable. But absorbs heat like crazy. Floors are wood and generally very tough.
If if were me, I would pour some concrete pads that elevated the container about 6 inches or so.
Yellow Jacket's idea about building a roof over a couple of containers is a pretty good idea. If you wanted to get real fancy a concrete pad or gravel between 2 containers would be pretty neat.
Since these things are ugly as sin I would consider planting some shrubs that would cover these things up.
My 2 cents worth of opinion.
