Nice buy with the 701s. I'm loving mine more and more every day.
I tend to use the following (and yes, these are intimately familiar to me, so take it with a grain of salt) to hear what I'm getting myself into:
Rock - Wolfmother. Good, heavy rock album with lots of punch, and a haunting organ of Doom. It's my favourite disc right now, so it gets on there no matter what I listen with.
Classical - Best of Bach. Complex arrangements really show off the 701's ability to seperate instruments, and the copy i have has a good "hall" recording sound, pulling the soundstage back. Music for 18 Musicians is in rotation right now too, but I am finding it hard to get into, since it's a continuous track with multiple movements, but I bought it off iTunes, so every track is seperated with 2 seconds of dead space.
Jazz - Mostly Buena Vista Social Club and Mambo Sinuendo. Great guitars, excellent production values, and a good range of musical style throughout the two albums. I'm also rekindling my love affair with Herb Alpert and the Tijuana Brass. These cans do jazz real good.
Metal - Protest the Hero, "Kezia" and Anthrax's new double CD "no-hit wonders". My Grados kill the 701s here in impact, but the sound is still wonderful. Same goes for Wolfmother above.
Electronic - Welcome to bliss. These phones turn a good stereo mix from exciting to mind-altering. Mouse on Mars' "Idiology", Aphex Twin's "Richard D James Album" and Beef Terminal's "Isolationist" are in heavy rotation.
Hip-Hop - The 701s are great here too. Public Enemy's latest greatest hits album, Danger Mouse and MF Doom's "Danger Mouse" and MC Paul Barman's "Paulelujah".
Country/Rockabilly - Stray Cats, Johnny Cash at San Quentin, Reverend Horton Heat, Matadors and Tiger Army are all in high rotation. Acoustic Bass sounds great here.