Dudes, Rush's 2112 is considered one of the least enjoyable epic prog rock songs by most, sure it's awesome, but if you want a really good epic song, start listening to more prog rock. There are a lot of epic songs hosted for free on this site, legally. I'll start you off with Yes' Close to the Edge, click this link for the playlist of it and their other major works.

If anyone enjoys it and wants some more, just PM me, I'll send you some more links.

Anyways, I love so many epic prog songs it's impossible to choose one. Right now I'm listening to Frank Zappa's the Grand Wazoo (Think it over), clocking in at about 21 minutes on the live version and 13 in the studio. Naturally I prefer the live version.