My biggest challenge when approaching any project is to stomp on my natural tendency to over-complicate things! Forget I mentioned waterproofing - I thought I remembered some talk of it on Patternreview.com - when I went back to look, the thread dealt with how to sew on fabric that was already water repellent (special needles - microtex, I think?) and how to waterproof the seams (using a special tape?).
Like you, I'm just going for a more "fashion" friendly trench - so I'm not going to go in circles trying to waterproof my fabric (and as you discovered, I don't think you can actually do that with fashion fabric anyhow).
I just got back from SB and picked up the sage fabric, matching sage hang-loose lining and these awesome buttons:

They are "seersucker" from SB (natch) and I got the aqua color. I'm not sure what I'm going to do with the topstitching yet - perhaps I'll keep with the mostly monochrome color scheme and try to find a matching color in a home dec weight.

I also picked up some muslin so I can whip up a...well, muslin...of the trench, hopefully this weekend.
