I had a vacation in NM in May of 2006... We went all over that area, Taos, Santa Fe, Acoma, etc. the weather was absolutely beautiful every single day.
I might recommend you utilize Albuquerque to start your search for tailoring/dressmaking/etc. I suppose Santa Fe and Taos might also have something suitable, though they are pretty small towns, relatively speaking. Albuquerque, though large, still has a "grass roots" type flavor, very strong and interesting cultural references, and I am sure you would have an easy time finding what you are looking for. Taos is a bit like other fancy shmancy ski resort towns, so you would be spending top dollar on anything there, though you are likely to find designer stuff there I would imagine.
Best of luck, and congrats to your family.