So I'm considering the Kona Dew as my all-weather commuter.
I'm 5'11" and 205 lbs--and usually carry all my gear (laptop, change of clothes, books) in a messenger bag that probably puts me closer to 220 lbs or beyond. (Actually, I wonder how much all my cargo weighs.)
Anyways, it is worth upgrading $100 to the Dew Plus which has Rigida ZAC19SL double-wall rims from the regular Dew's Rigida Cyber 10 single-wall rims (or the Alex ZC1000's on the '07 Dew)? It's not like I've got an extra 100 bucks just sitting around (and the Plus' disc brakes aren't really much of a selling feature to me), but I'd also rather not be spending my time having my damn wheels trued when I could be riding!
Those two things that you mentioned are an absolute must on any bike IMO.
I am a car free guy who rides every day and while I am under 200 pounds I often pull a large cargo trailer with over 300#'s on it. The double wall rims are a must.
Some people disagree about disc brakes but I think they are better for a few reasons.
#1. Less maintance. My wife has rim brakes and I have disc's. Even though I ride about 5 times as much as she does I spent 5 times as much time adjusting her brakes. Seems one side is sticking or there is some rock etc stuck in the brake pad. With my discs I occasionally (every few hundred miles) turn two screws to adjust for pad wear and I'm good to go. I bet I have not spent 5 minutes on them in the 5,000 miles I have put on this year.
#2. They stop better regardless of weather or if your rims are clean or not.
#3. The pads last for probably 7-8,000 miles in my experience.
#4. Rotors are much cheaper to replace then wheels and my last rotors lasted 15,000 miles and cost about 15 dollars a piece to replace.