The DWS (Dry/Wet/Snow) are all-season tires.
The DW (Dry/Wet) is a summer tire. It doesn't rate as well, and has half the wear rating and overall does not rate as well.

 

That depends...

• Are you looking for a good all-around tire that will give good tread life and be usable in light to moderate snow? If so then you want the all-season tires (i.e. DWS).
• Are you looking for ultimate dry grip so that you can take your car to the track on the weekend and flog it to within an inch if its life? If so then you want summer/performance tires on your car (i.e. DW).

 

All All-Season tires are a compromise, but the difference in wear rating makes them worthwhile to me. 540 vs. 340 for the DW's. The 3 tends to burn up tires pretty fast anyway. I have gone through 3 sets, including the OE Bad~years, in 60k miles. I do drive spiritedly on the roads (as the traffic allows,) but have not auto-Xed or Rallied in 25-30 yrs now.
Plus they are known for a better ride than most. We installed a set on my wife's Pontiac Vibe this winter and we BOTH love them. She is hard to please when it comes to tires, and so am I.
Great tire, reasonable price, good ride and an excellent wear rating. That's all I can say 'bout that.

 

I'm pretty much in the same boat in that I no longer "need" summer rubber (hence the Michelin Pilot Sport A/S tires on my 3). The good news regarding the Michelins is that they're fast approaching 30,000 miles and still look good. I'm thinking 40,000 miles is a lead pipe cinch with 50,000 miles on the one set an outside chance.

 

all years

 

I should have mentioned I live in California. I don't think I'll ever be driving in snow (but there is plenty of rain). I found a good deal on Yokohama YK520s (~$400 for all 4, shipped). The DWS tires are about $540 shipped, so about 35% more expensive. Is it worth it for the kind of climate I'm driving in?

 

The only place that sells 520's is Discount Tire/Tires America.
They only rate fairly and 520's as w/most Yoko's become noisy as they age.
The Contis will give a better ride and be better in the rain (hydroplane resistance) than will the Yoko's. Trust me, I have owned Yoko's in the past.
The cost difference is up to you.

 

As far as the mpg i also have the 2.0l w/5 speed. Ive never gotten below 30 mpg and hover around the 34 to 37 mpg area. Driven sensibly i can get almost 40 highway.

 

Yes, but that's because you are a kNuCkLeHeAd, Gary!!