I might do a few places on the net but i dont know of any site that saves files that long. a yahoo mail account will get delete.
I'm going to make 3 usb thumb drives then bury them 5 miles apart. How do you suggest I weather proof them?
Sealed plastic bags should do the job.
Also put it in a metal box of some sort, otherwise it might get damaged by pressure etc.
And I'd recommend storing your wallet somewhere on the net, otherwise you might run into bad luck if you get out of jail after 20 years and they had the idea of building a new skycraper cityscape at the places you buried your "Money".