If you're serious about a bike, get a chromoly (chromium-molybdenum steel) frame. They will flex just a tad and provide a more comfortable ride. They also last longer. Notice that the Long Haul Trucker, Trek 520 and Novara Randonnee have chromoly frames.

Many of the mountain bikes I've seen lately have carbon fiber or aluminum frames and shock absorber suspensions; they're lighter but they don't flex which is one reason shocks became necessary. I have an old Scott mountain bike w/ chromoly frame, no need for a suspension fork- I like a simple bike. All I've done with this bike in 20 years is replace tires and chains. I took it in to REI for their bike maintenance class and replaced the tires, chain and other stuff and then learned to adjust everything -- good class.

One other thing you'll want on a bike is plenty of braze-ons (threaded eyelets et al) for attaching racks and whatever else you need to attach. This is another reason chromoly steel is the way to go. The Surley Long Haul Trucker has plenty.
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