You might think this one odd, but if you've never listened to Cocoon Crash by K's Choice, I recommend it... it's more "chill" than epic, but it seems to have been written from a very personal place. I like to write, and that was always one of my favorite background albums.
I also recommend:
Incubus - Make Yourself
Foo Fighters - The Colour and the Shape
Evanescence - The Open Door (if you're down for some gothic-style piano driven woman rock, anyway)
Pink Floyd's work is a good example of epic experimentation (their earlier albums before Dark Side Of The Moon) and Prog Rock (their later albums including The Wall) so it is good if you want to go in that direction with some tunes (kind of like you did on Weezer in 2008 with "Dreamin'") As other posters mentioned, The Ramones are excellent for straightforward Punk Pop as they were one of the bands that invented the stuff. If you want an example of a great Ramones track, try "Comeback She Cried, I want Out" which is one of the bonus tracks on Road To Ruin (Recent Edition). Also, try some Dramarama, especially their first albums, as they are a great alt rock band with a pretty wide-ranging sound. For classics, I agree with the posters about The Who as they also set some classic sounds and epic albums such as Who's Next and The Who Sings My Generation. I could go on for hours as there are so many great albums out there, so I will finish with any and all albums by The Beatles and The Kinks. They were the pioneers of great Pop Rock and, in the case of the Kinks, grandfathers of Alternative Rock. Listen to their classic album Give The People What They Want and especially the track "Around the Dial" for an example of this.
Thanks for asking us listeners, and keep making great, epic rock with =W=eezer! I'm thoroughly enjoying all these releases lately. Keep 'em coming!
Oracles and Odysseys by The Zombies
Blue by Joni Mitchell
The Score by The Fugees
Whoa! Nelly by Nelly Furtado
Ziggy Stardust and Spiders from Mars by David Bowie
Soundtrack from "Rock N Roll High School" mostly by The Ramones
And, yeah, Pinkerton... seriously, it was awesome from the day it came out and I put it on my boom box and wondered and wondered what was happening.
Also, I tend to like songs/albums that deal with a larger issue like the environment or social issues, but in a really large way. Unfortunately, there aren't too many that really make you think, you know? Or, that can possibly impact the world... that would be epic!
Our Lady Peace's Spiritual Machines has a mild concept going for it, is really interesting on a sonic level, and has some mindblowingly great stuff on it. "The Wonderful Future" is a great, "epic" sounding song. "Are You Sad?" and "Life" are a couple other personal favorites. This was before their more pop sounding singles, which I also enjoy, but it's seemingly not where you're going with this. I don't know if I like every single song on it, it took a few listens for a few of these songs to click, but I like enough of the album and it might be worth giving a shot.
I'll also agree with the "masturbatory" claims regarding Pink Floyd. I love their early material with Syd Barrett (and his two solo albums), but after that there's something a bit too... pretentious about it? Not sure if that's the best way of putting it. I suppose sonically there might be an interesting thing or two to pick up from them, but I've never cared for their songwriting after Syd left the band. I know it's kinda blasphemous to say so, but it's how I feel. Piper at the Gates of Dawn (their first album) is a pretty cool record, though.
Otherwise, a lot of the stuff I'd name would be stuff you've already been aware of for years - the first two Oasis records, various Beach Boys albums and the Smile material, etc.
Yes, to Pink Floyd, and Rocky Horror Picture Show (various), I would say Pixies/Nirvana but that's been gone through, Lullabies To Paralyze (QOTSA), Pinkerton (Weezer), Maybe some older stuff? Like old Jazz guy's, Muddy Water, and such.