Yep, I agree that their sizing is all over the map. I have quite a few pairs, and they range in size from a 5 to a 7. Yikes! I would probably not buy them online for this reason. I've heard the sales staff can be quite helpful, however; if you talk to them on the phone about your own foot quirks, they can point you in the right direction, or help you get the right size.
One thing that's worth noting: the company purposely makes their various styles in different widths etc to fit different shapes of feet and legs. So, for example, there are a few styles that are intentionally made to be narrow in the calf, so those are good for people who have trouble with boots always looking like galoshes on them. Or, if you've got short, wide feet, they have some styles that have a big, roomy toe-box. Again, the sales assistants can tell you what will work with your feet and legs.
Another knee-high style that works with all size calves is this one:
http://www.fluevog.com/code/?w.....ourID=2145
...because you can adjust the calf sizing with the laces. Not everyone loves the chunky sole and spool-shaped heel, though. But I think they're cool -- and fun and arty, which is what you said you were looking for.