I think some of the problem comes from the fact that the coats are often lined with a different fabric than the outer and the companies often don't take the time to split them!
I have a J Crew coat and a Club Monaco coat and both are quite nice. My J Crew one is definitely the winner for quality for price. It is two years old and looks like new. I think it was a much better value than my Club Monaco one, which is lovely and very good quality, but not the same phenomenal quality as the J Crew one. And J Crew carries petites. Angie has a J Crew one too and I know she is very impressed with how it has worn over the three years she has had it--she mentions it often!
My suggestion would be to not worry too much about the wool/other fiber division, up to maybe 20% other fiber. 100% wool can be lousy quality wool and pill and fall apart in a cheap coat. Also blend can also add durability--I know 100% cashmere is not nearly as sturdy for a coat as a cashmere blend, so thoughtful sources recommend a blend over a pure cashmere coat.
Try on a J Crew coat, if you can. I bet you'll love it.