I found the wool Rivet to be slightly slimmer than my cotton Rivets, but not quite as slim as my Oxford cloth Rivets....so they fit somewhere in between the two. I usually take a 34 in the standard Rivets - I sized up to 36 and got only the waist taken in on the Oxford cloths and they fit pretty similar to my other 34s. I tried the Wool in 34 but they were just a tad too slim for me. I think sizing all the way up to 36 for those would have been too much.
Beatlegeuse- thanks, probably order 32 and make adjustment from there.