C# minor.
The key of the Moonlight Sonata, Rachmaninoff’s Piano Prelude, and Chopin’s Fanatsie Impromptu.
Gimme a ‘C’, a bouncy ‘C’…
Well, since clarinets and trumpets are B-flat instruments (a “C” played on them is actually a B-flat on a piano), it depends. I played clarinet and most of the band music I played was in B-flat major. Anything more than 3 flats or sharps (in my tuning) was unusual, though I saw more of that in orchestra.
Now the flutes (a C instrument), who I sat next to, had flats all over the place but that didn’t seem to be a problem with them
I’m going to go insane trying to place this quote. HELP!!!
D minor.
It’s a synesthetic thing. 
flinch
so…many…sharps…
(quoth the amateur.)
D minor which is the saddest of all keys, I find. People weep instantly when they hear it, and I don’t know why. 
Snooooopy might be able to tell you why.
Sharps are good! A bitch to read (especially when your start hitting double sharps), but they feel good in the hand. Do you know which key best fits the shape of the hand on the piano? B Major. Play it and you’ll see why. Shorter thumb falls on the white keys, longer fingers on the blacks. For similar reasons, jazz and blues pianists love the F blues scale. You can play wickedly fast with that. Not like C. C gives you carpal tunnel.
In terms of sound, I don’t really have a favorite key. I don’t have perfect pitch, so I can’t tell whether a song is in C or B flat. As for playing, I really like D-flat major. (I hate reading it, but I like sitting down and improvising in it.) F blues is also good on the fingers. G blues and A major. All comfortable keys for me.
Please don’t tell me I’m the only A minor lover here.
I also like Em. It’s a great key for a reel. Hadn’t spotted in it the Metallica repertoire yet…
Bahh… A minor is just a C major that needs Prozac. Too vanilla.
C# minor is nice, as someone already mentioned. As for major keys I find B flat, D and F all quite nice. And after I thought about this I realized they are the notes in a B flat major triad. Hmmm.
D minor is pretty cool too, I must agree.
The one to Shania Twain’s dressing room.
[sub]I almost said “dwessing woom”[/sub]
“Gimme a ‘C’, a bouncy ‘C’.” was the catchphrase of one of Martin Short’s recurring characters on SCTV. He was playing an old song-writer who claimed he could write a song about anything.
That’s exactly who I was thinking of. Thank you, Bryan!
Heh, I don’t really associate with colors, per se, but more with moods. And you nailed E major, as I also picture it as a royal, majestic key. A major is also bright and cheery (not cherry ;)). D major is the key of life, which is probably influenced by my listening to Pachabel’s canon one too many times, as the canon sounds like a life story to me.
You’ve upset me now. 
I find Am crunchy and refreshing like a good Braeburn apple when applied in the right way.
There now, Kytheria, we’ve gone from colours into flavours. How mad can you get?
I usually see colours as well, though, but different ones from the ones you mention.
I’m not insane! I’m not insane! runs around squeeing happily in the library
…
realizes she’s being stared at everybody
woops
C# minor is a real bitch to play, quoth the pianist, but it sounds wonderful.
I like to play the guitar, so that obviously influences me…
Blues: Eb a la SRV or Cm a la Albert Collins.
Rock: Hell, it’s pretty much all Em/G anyway
Jazz: Does it really matter? 
Actually F always seems to lean towards jazz to me. (So can G if it’s phrased right)
Dm is totally the saddest key especially when someone pulls a slow arpeggio. A nod definitely goes to Bm for blues, although for some reason, I tend to also associate that chord with sad Spanish scales too… that can sound really ethreal.
D reminds me of Pachabel a little unless its on a Martin–then the chord kind of goes “Rocky Mountain High.”
E is totally a majestic chord. It always sounds so full.
F# always sounds charged, aggressive, or amped to me.
Am is a total favorite of mine on the guitar. I feel like it has this warm soothing feel–like the color of honey stained wood.
A is really straight forward to me. It kinda says “Hey! Here I am!”
C is great. It is really cheery to me in just about everyway you play it. It can sound really hippie-happy, or Gypsy Kings happy (to me). I wonder how much reggae works with in F and/or C.
I have never really used B unless I’m dropping my guitar by a half step and then I really look at it in my head like i’m playing a deeper, more soulful C for blues. (the Sky is Crying by SRV is a really good example of that to me.)
I love the color schemes in this thread! They are awesome! I never thought of them as colors but that totally makes sense!! I can’t wait to get back to my guitar and try out the “color wheel”
As a bassist, I like playing in just about any key, though I prefer to stay away from anything with more than three flats. Sharps don’t bother me.
As a guitarist, I prefer to stay in D, E, Em, F#m, G, A, and Am.
I hate playing along with most piano players, because pianists seem to be in love with keys like Eb and Ab, both wretched keys for guitarists. On bass, the key isn’t that big a deal, but I still don’t like Eb because it takes away the bottom of my instrument’s standard range (the lowest note on a 4-string bass is E), but that can be fixed by playing a 5-string bass, which extends the low range down to B.
How do I hear different keys? The only thing I’ve specifically noticed is the key of B-minor. B-minor has a certain “tension” to it. Judas Priest used B-minor to great effect. Fairly often, a song would be chugging along in the key of A, and then when it came time for the guitar solo, they would shift up to B-minor. As the guitar solo ended, they would shift back down to A for the final verse/chorus. “Heading Out To The Highway” is a good example of this. For some reason, it just doesn’t work in other keys. For example, playing a song in G and shifting to A-minor for the solo doesn’t create the same kind of tension as shifting from A to B-minor.
I’m afraid the only memorable theme I’ve written is, apparently, in C Mixolydian mode: I just spent over an hour trying to find out what key, or even mode, it is in, since I havent taken formal classes for over 25 years, but apparently none of them have two semitones with only one note in between, rather than two or three.
The “home” note is C, and it uses only these notes:
C
A
A#/Bb
F#/Gb
F.
Now, I can’t fit it into any mode or key unless I remove F#. Then it fits into the above mode, even though F sounds less natural. It sounds like an outlier to me.
But the theme I made is very sad, yet hopeful. Perhaps I hear some similarities to D Minor, but starting on C makes it more hopeful?
Blues in F or Bb major. Jazz clarinet ectasy. 