You might look at the FX bikes from Trek. They omit the shocks on the fork and seat post, and ride more like road bikes than mountain bikes. If the crushed limestone is large, then you might want 700x35 tires rather than the stock 700x32's.
The 7.5fx is a 9 speed and lists for $789 but you can probably find a one for less since the new models are on the way.
I have the 2003 version, 7500fx and it has been great. BTW, I am 6'1" and weigh 205.