This one goes to 11…
Rimsky-Korsakov’s Scheherazade, but not just any recording thereof. The Leopold Skokowski Phasse 4 Stereo on London label recorded in 1964. Looks like this.
Hook up some seriously nice speakers, crank it wide open and take your heart medication beforehand.
Russian stuff can be particularly epic. In addition to the ones already mentioned, I’d add Mussorgsky, especially Boris Godunov. A Night on the Bare Mountain–more popularly known as “Night on Bald Mountain”–and Pictures at an Exhibition are quite stirring, but bear in mind that the orchestral versions that you usually hear were arranged by Rimsky-Korsakov and Ravel, respectively.
Another good but often overlooked Russian work is Borodin’s opera, Prince Igor. You’ll sometimes hear the “Polovtsian Dances” performed as a stand-alone piece, but throughout the opera there’s quite a bit of grand music and choruses.
I love Wagner, but if you’re looking for entire works that are consistently “grand” in mood, you’ll have some problems. Rossini once said of Wagner that he has “beautiful moments, but bad quarters of an hour”–which if anything is an understatement. For each heart-pounding set piece–think “Ride of the Valkyries”–there’s a half-hour or so of Wotan droning on about vows and fates and a lot of other stuff that’s important to the story and character development, but makes for some tedious music (at first hearing, anyway). Those ponderous moments tend to slow down the action quite a bit.
Buuuuuut… the climaxes to each of the Ring Cycle operas, and Tristan und Isolde (the “Liebestod” will send shivers up your spine), are just incredible feats of music unlike anything else you’ll ever hear. They’ll more than make up for all those hours (seriously–hours) of slower and grippingly undramatic moments that precede them (with occasional flashes of pure brilliance), and arguably those slower moments are essential to feeling the full outpouring of emotion that comes with the climax (sorry, it’s hard to avoid orgasmic metaphors when talking about Wagner’s music).
Nevertheless, it’s good to know what you’re getting into before starting the entire 15+ hours of the Ring Cycle–it might be better to start with a “greatest hits” compilation.
Which is as good a moment as any to mention the Lorin Maazel recording - Der Ring ohne Worte (The Ring without Words).
Some particularly good Wagner “moments” (in quotes because they’re a little more extensive than your typical moment). Some of these** Götterfunken **already mentioned:
*Rheingold *finale.
Acts I and III of *Die walkuere *(too lazy to code an umlaut). There are a few slow moments in these acts, but most of the long drawn-out bits are in Act II. On the other hand, the finale of Act II is my third favorite bit of the opera (after the finales of Acts I and III).
*Siegfrieds Rheinfahrt *and *Siegfried’s Funeral March *(from Goetterdaemmerung).
Finale of *Goetterdaemmerung.
*Prelude to *Tristan und Isolde.
Liebestod *from *Tristan und Isolde.
*Prelude from *Parsifal.
*The Transformation music from *Parsifal.
*If you want an entire Wagner opera that’s relatively easy to listen to, Der Fliegende Hollaender, while not as brilliant as his later stuff, is still packed with great stuff, and is fairly standard length for an opera: about two and a half hours (by contrast, that’s about the length of Act I of Goetterdaemerung).
Can’t believe there are almost 25 posts about “epic” classical music and no one has mentioned Aaron Copland! :eek:
El Salon Mexico
Billy the Kid
Appalachian Spring
Rodeo (you’ll recognize the fourth dance for sure if you eat beef!) 
And of course, his Third Symphony, which has a little known themefor the fourth movement. 
I would recommend:
Not just the Ode to Joy, but the entire Ninth Symphony. I think it’s the most extraordinary piece of music ever written.
Dmitri Shostakovich’s Fourth & Fifth Symphonies
Black, Brown & Bie**ge by Duke Ellington. Try to find the version with Mahalia Jackson singing “Come Sunday.”
J.S. Bach’s *The Passion of St. Matthew *is not my favorite Bach piece, but it is epic, and it may be your cup of tea
Ignore the nay-sayers. Wagner was a fucking genius and the entire Ring Cycle is well worth listening to. Actually, I haven’t heard a bad opera yet from Wagner’s pen.
Carmen by Georges Bizet. This isn’t an epic, but if you want to listen to good opera, I highly recommend it. In fact, I would say that if you don’t like “L’Habanera,” you aren’t going to like opera.
Mozart’s Concerto No. 20 in D Major for Piano and Orchestra. Plus, any Mozart symphony is worth listening to.
In terms of the emotions it can invoke, I would also suggest *Dialogue of the Carmelites *by Francis Poulenc.
Have there been any nay-sayers?
Neigh.
Some of my favourites:
Organ Symphonyby Camilo Saints Saens.
Jupiter, by Gustav Holst.
Finland, by Jean Sibelius.
New World Symphony, by Antonino Dvorak.
Estancia suite, by Alberto Ginastera (here, is an example).
These are all great suggestions and my ears (and associated music-appreciating portions of my brain) thank you all!!! 
Excellent, as is Mars.
Coincidental to this thread, I was listening to Bolero (a ponderous 17 minute version) on my drive this morning. It’s slow to build, but once it does, let the ass-kicking commence.
You may find many of the pieces mentioned in this thread on YouTube.
Wagner, Overture to Tannhauser
Wagner, Prelude to act 3 of Lohengrin
Shostakovich, Festive Overture
Mussorgsky, Coronation of Boris, from Boris Goudonov
Rimsky-Korsakov, Procession of the Nobles, from Mlada
Liszt, Les Preludes
Liszt, Totentanz
Beethoven, Symphony #3
Beethoven, Piano Concerto #5, the “Emperor” (called that by Johann Baptist Cramer, its English publisher. But he was right.)
Ravel, Daphnis and Chloe (Two truly epic parts are at the beginning and end of the second suite: Lever du jour (daybreak) and Danse générale. But the entire ballet is worth a listen.)
Dvorak, Carnival Overture
Debussy, Fêtes (second of three nocturnes for orchestra)
Debussy, La Mer (last movement)
Smetana, Moldau
Rachmaninoff, Piano concerto #2
Rachmaninoff, Rhapsody on a theme by Paganini
Handel, Zadok the Priest (coronation anthem for George II)