I'll echo Robow's advice here. What you're looking at/for is in fact what I've 'created' (not quite finished yet) over the past four years; as I've realized that my riding consists and will consist mainly of a) fastish commuting and b) much longer on/off road touring rides. Re. the latter, not 'mtb'ing' as such, but rather light(ish) off-road, what the Euros call trekking. Bought a Giant Rainier in '05, spent the first two years with it constantly looking at different bikes, then realized that suitably modified I already had the basis for what I wanted.

The problem now is simply that most decently-specced h/ts (LX/X7 or above) are wannabe xc race bikes -- hence no rack mounts (if that matters/it did to me) etc.

However, there are still some very good candidates for this usage, though most will need upgrading over time. Any of Rocky Mountain's recreational xc hardtail range (e.g. Trailhead); Specialized Rockhopper (the Pro model is pretty well equipped stock), or the 09 Hardrock if upgraded; Kona's base Kula model retains rack mounts, though the geometry's a bit off I think for road use -- bikes of that kind come to mind.

I agree re. hydros, by the way; my Rainier came with horrible Hayes so1e things, which I junked last year for a set of BB7s/SD7. Pretty much got the bike where I want it (LX crank, 717/XT wheelset, X9 shifters/cassette 12-25, tires change according to use); it goes anywhere/does anything I want it to do.
Final thought: most of the really desireable 'on/off road/expedition' tourers are pretty much mtb based anyway, so I reckon I've got pretty close over time, though can't deny I really, really want something like a Thorn Raven Nomad Sport Tour or similiar -- maybe someday