I wish I'd seen your post sooner. Since if your in the PNW, you could've attended the dui demo days at Les Pier in Tacoma this weekend and test dived any dui equipment you wanted.
I just bought a dui cf200 online and had to rely on the measurements chart. The critical thing here is that you MUST have someone else measure you in order to get accurate measurements. If you don't have someone, find a local tailor; I bet they'd do it for you for a modest tip.
Another important tip if you're using the online size guiedes, they are different for different dui suit models. Make sure you're looking at the chart for the model you intend to purchase.
I called dui first and gave them my height, weight and shoe size and asked if a standard xl-s would fit me. They said it wasn't possible to know without taking the full set of 15 measurements (actually they were most interested in less than 10 of them). Once I had been measured I saw that, in general, I was in range on the xl-s. I called dui again and read them off a series of measurements. They told me that while no off the rack suit is going to fit anybody perfectly in every single way, that the xl-s sounded like a good fit for me. I bought it and I'm very happy with the fit. I am 5'11, 208lbs, wear size 36-38 waist pants depending on the cut, and size 10 shoes. But using the dui measurements guide, my waste is 43in; so that's why it's important to follow their instructions in order to get the proper measurements.
Here's at least a partial list of dui dealers in the Pacific NorthWest, since that's where you appear to hail from.
http://www.dui-online.com/newsite/dog_lesdavis_2003.htm
Hope that helps.
-k