April,
Dare I say that I am far harder to fit in wovens than you are! And I'm POSITIVE that I'm far lazier about ironing. So I sympathize, but if I can find woven tops, surely anyone can
I have some wovens from NY&Co that Tanya gave me which are amazing because they don't require ironing and they fit over my massive bosom (well, there is a buttondown that doesn't, but it works with the top button undone and a cami underneath). They have a very high stretch content, which is great because it makes them fit and relieves me of any ironing obligations, but the drawback is that they don't look quite as crisp as other wovens and the material is rather thin. Still nicer than knits, though.
Woven tops that aren't buttondowns seem to work best on me. I haven't found a single buttondown that will close over my chest but still fit everywhere else. Angie has witnessed this phenomenon. Tops that have side zips are my friends. I guess since your fit issue is in the shoulder rather than in the bust, this might not help you necessarily, but it's worth considering what kind of woven top you're trying.
Honestly, I would be happy to just alter my tops if altering worked for me, but it doesn't. My issue is that if I go up in size, it is way too big in the shoulders *and* the waist. The waist is easy enough to have taken in, but the shoulders? There is no hope if the shoulders don't fit. I mean, I'm sure an extremely skilled seamstress could do it, but it would probably be very costly and there is lots of potential to screw it up. I don't think it's worth it for the H&M top I tried with Angie :p
So with that said, I think since your shoulders are your "fussy bits," it is probably a lot easier for you to get the necessary alterations as you can fit your biggest part and easily have the rest taken in.
By all means post pics. It's the only way to know! I remember when Angie did the blog post on Talbots, she found their smallest size much too big though, so I am skeptical!