Really depends on what mood you're in.
I've always liked "Rhapsody in Blue" by Gershwin, it's a fun listen. As is "An American in Paris."
Another personal recommendation would be the Planets Suite by Holst. I've been listening to that since I was like 9...
If you're thinking of the choral route, I'd say anything by Eric Whitacre. Especially "Sleep", "When David Heard" and "The Seal Lullaby."
The Rite of Spring is good, but is a bit of an acquired taste imo. If you've seen Disney's Fantasia, you may be familiar with some of it.
Prince Igor's an opera, and a fairly long one at that but if you can get a recording of the Polovtsian Dances, you'll get some of the highlights (along with the overture, I think)