Re: Good instrumental songs?
Since you have keys, check out the Booker T. catalog for some classic grooves.
And for fun, there are a bunch of '60s surf instrumentals.
If you're in a retro mood, look to the big band era: Stompin At the Savoy, King Porter Stomp, Take The A Train, Sing Sing Sing, etc.
Classic pop/rock/jazzish tracks: Pick Up the Pieces, Put It Where You Want It, etc.
Or more ecclectic: Zappa's "Peaches En Regalia" :)
For more fun, there are plenty of cool TV themes, even if they have lyrics, you can do them as instrumentals with a guitar por horn playing the lead. For that matter, you can take most songs and just have an instrument play the lead vocal to make the song an instrumental.