I only listen to Mogwai or sometimes GYBE! when I'm doing work

Just listen to a bunch of Post-Rock. Mono, Do Make Say Think, Explosions in the Sky, Godspeed You! Black Emperor, etc.

Four Tet
Explosions in the Sky

Also, alot of other post-rock bands are very instrumental. Godspeed you blacnk emperor, mogwai, etc

Wow, I was listening to that as I read your post.

Opeth - For Absent Friends, Patterns in the Ivy, Requiem
Zeppelin - Black Mountain Side
Pink Floyd - Any Colour You Like

Edgar Winter - Frankenstein (one of rocks all time best instrumentals by far)
Led Zeppelin - Black Mountainside, White Summer Black Mountainside
Rush - La Villa Strangiato
The Who - Sparks
Allman Brothers - Jessica
Zappa - Peaches En Ragalia
ELO - Fire On High
Eric Johnson - Cliffs Of Dover
Allman Brothers - In Memory Of Elizebeth Reid (highly recommend it)
SRV - Scuttle Buttin
Zappa - The Gumbo Variations
" - Black Napkins
ELP - Toccata
Pink Floyd - One Of These Days, Marooned, On The Run, Any Colour You Like, Interstellar Overdrive, Atom Heart Mother
Malmsteen - Evil Eye
Santana - Europa, Butaku
Yes - The Fish
Zappa - Son Of Mr. Green Genes
The Beatles - Flying
Allman Brothers - Hot lanta
Alice In Chains - Whale & Wasp
Van Halen - Eruption

All I can think of for now...

how dare I leave out green onions by Booker T & the M.G.s