I'm a big fan of instrumentals by rock bands.

Stuff like Jade's Song (Badlands), Midsummer's Daydream and Fantasy Serenade by Rik Emmett of Triumph, Mood for a Day by Steve Howe, etc.

If you know of any other instrumentals you can recommend, please let me know.

Thanx in advance,
Ibanez S470 (2005 Black)
Washburn D10SCE
Vox AD30VT
Midnight Moodies- Joe Walsh
One Of These Days- Pink Floyd
Clap- Yes
La Villa Strangiato- Yes
Asshtonpark- James Gang
In Memory of Elizabeth Reed- Allman Bros.
Any Colour You Like- Pink Floyd

yeah, that's a good start
How to achieve Frank Zappa's guitar tone:
Quote by Thefallofman
Step 1: Buy a Gibson SG
Step 2: Insert Green Ringer, EQ, 3 dead squirrels and a microwave into said SG
Step 3: Plug in and freak the **** out.
I'm not sure if you can classify The Ventures as classic rock, but just about everything they did was an instrumental cover of a song, no lyrics at all.
Since you like Mood for a Day, conside Horizons by Steve Hackett.

Another favorite is Red by King Crimson. (If you want to hear a cover, search the riffs & recordings forums. Asomodai did a very good cover of it a while back).
(Slightly outdated) Electronic and classical compositions by m'self: Check 'em out