Had a thought...
If I were going to build a utility bike from parts, here's what I would build and why:
Frame: Surly Long Haul Trucker. Price is low at about $400 and it has the geometry and braze-ons for utility work.
http://www.surlybikes.com/longhaul.html I'd toss the fork and get a rigid mountain bike fork with a disk brake mount. Disk brakes have proven themselves to me in both power and maintenance requirements.
Wheelset: Get someone to build a wheelset using the hubs of your choice as if it were going to be on a tandem. Tandems carry two folks and sometimes gear, so the wheels have to be tough. If you're going to use a front disk, make sure the front hub is disc compatible. Use rims designed for downhill racing (that's the toughest environment for wheels). The rear has to be rim brake compatible, the front can be that or disk specific.
Brakes: V-brake rear and disk front. Rear brake doesn't matter much (any v-brake will lock the rear wheel even on pavement), but for the front disk, I'd go Avid BB5 ($39 online) and the largest rotor you can justify. I find 160mm just fine for mountain biking, but a 200mm would stop that much better without being much more expensive. Don't bother with hydraulic disk brakes. They "feel" better, but are harder to maintain and you can't just go into any shop and get a new brake line or brake lever, but any shop will carry a brake lever and cable compatible with the BB5 (it's a mechanical brake, btw).
Controls/drivetrain: Any cheap V-brake lever, any cheap shifter that works with your drivetrain. I'd go 1x9 with a 32t front ring and an 11-34 rear cogset (I've climbed 2000ft trails with a 32x32 low, a 32x34 is even better). I'd get the longest cranks my legs could comfortably use (longer cranks = more torque). I currently ride a 180mm crankset, but if you have less than a 32" inseam, go 175mm. I'd use whatever's cheaper and available among gripshift, shimano's trigger shifter, or even a thumbshifter (Shimano Barcons or Barcons with Paul's Thumbie adaptor). There's always internally geared hubs, but I know next to nothing about them and am not that comfortable with them. For bars, I'd use On-One's Mary bar. I've ridden them and find them very comfortable. They're a hybrid between a mtb riser and "utility bike" bar.
http://www.on-one.co.uk/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=6&MMN_position=5:5Misc-
Headset: FSA The Pig DH headset. You won't find a tougher headset for the price ($32 shipped for mine).
Pedals: whatever works for you.
Bottom Bracket: cheapest sealed unit that works with your cranks. The only real difference is weight
Tires: something in the 1.5-2" range. I'd probably use mtb semi-slicks (light tread in center, a bit more on the edges). I would not use a mtb knobby. If you ride a LHT big enough for 700c wheels, then I don't know what to suggest due to ignorance about 700c offerings, but go fat as possible.
Tubes: Heavy duty butyl tubes with Slime sealant
Seat: Whatever fits your butt.
Seatpost: whatever connects the seat to the bike for a good price
Stem: whatever gets the bars in the position you want.
I'd choose the seat, seatpost, and stem based on the riding position I'd want, which would be fairly upright compared even to my mountain bike. I'd probably set the bars about an inch or three above the seat (they're even on my bike now).
That's what I would build for "utility". It's simple, not terribly expensive, and tough. The components are all well known and proven in the field. I think the entire bike could be built for about $1k at full retail (the biggest expenses are the wheelset and frame). It would cost less for me since I have some of the parts on hand already. Judicious shopping online will drop the price as well.
Just a thought...
Chris