You know, this really all depends upon the setting you're playing in...what type of music and what kind of instrumentation and stage setting. I actually disagree with some of what's been posted.
As a guy who's played in a bunch of reggae and Jamaican music bands, I don't want a lot of mids. The instrumentation is arranged in such a way that each instrument covers a sonic neighborhood and when people cross into each other's sonic territory it gets bad fast.
Fer instance, its my job to cover the lows, and I roll off most of everything above mid/low. If I don't have some boost in the 40-200hz range it sounds wrong. Now, for most of the mid-range, the keyboards will cover that. I don't need to be there and only get in his way...the same way a keyboard gets in my way if he's wanging on the keys with his left hand in the octave or two I play in.
The guitars cover the mid high neighborhood and keep it there. If you notice reggae players, you could get rid of their bottom two strings and they'd never have a problem...they're not playing full 6 string strum chords.
The drums do several things...the kick reinforces the low lows, the snare is in the mid/mid-high region, and the hi-hat covers the very top, above the guitars.
If you add all this into the syncopation that is the heart of the sound it all works out.
Now, for rock, funk, jazz, etc. it's a different story...but there's a fine line between being in the mix and being out front of the mix. Most of your highs will get swallowed by a band (often if playing funk/rock I flatten out my high end and any fret/finger noise is lost in the mix anyway. But if you pull too far back on your lows, you end up with an anemic mix.
Don't need any distortion in my signal at all. I want warm tone, but not at the expense of clarity. In a band setting, I've always felt that whatever effect that everyone tried in their livingroom needs to be turned down by about half...reverb, overdrive, phase, whatever it is, once you get in a band, the 'solo' setting is way too much.