Also coming from a strictly California work environment - the SF Bay - our dress styles have been a bit lax - at least with every SM I've come across here (except for one very fashionable PSM who now works at Ford's and one up in Ashland, both male...).
When I was EMC'ing, my SMs always wore jeans, sneakers and T-shirts. However, the T-shirts were always clean, no holes, and generally interesting. You never know what you're going to be doing, so you dress for movement and getting dirty. I can say I've NEVER worn a dress or skirt to a rehearsal, simply because I'm not a dress-wearing-person, and I feel much more comfortable in jeans. I also made a point for several years not to wear sandals or dress shoes, as I felt cross-trainer sneakers were the best thing for me to move quickly and quietly around the rehearsal hall.
However, when I started working with a new theater with new directors, I found myself dressing to their style and conforming with their attitudes (more relaxed). I worked with two men who always wore shorts, flip flops and generally an open button down short sleeve shirt over a t-shirt. I started wearing sneaker-like sandals, and sometimes flip flops, along with shorts to those rehearsals. Granted, these were staged reading-style musicals, so there wasn't the need to run around to move things (except resetting a music stand), but it was something new for me - and I didn't feel any less a part of management; I looked just like the boss.
With my resident PSM job, I really have no idea what I'll be doing in any given day - aside from my usual daily tasks. There have been days where I've worn a blouse, dress slacks and heels, and then found myself schlepping boxes in the basement, crawling on the dance floor, mopping, dealing with clogged toilets, you name it. I've gone back to my adoption of the cross-trainers, jeans and solid-color T's. I also work on a mezzanine level, so at any time I run out of my office and sprint up the stairs to any of my 5 studios to help fix sound systems, deal with injuries, set up props, etc. There is no elevator access to my office.
In past years, while the rest of our admin staff has casual Friday, my ASM started "Fancy Friday" where we would dress up for the day. We did make a point to bring different shoes and alternate clothes in the case that we would be doing something dirty.
I'll say that my style is what it's always been, and sometimes, if it's a special day, like Dress Rehearsal or one of our 4 performances, I will wear makeup and heels - but never for rehearsal. Working with dancers, the makeup melts off just minutes into sitting in a studio, and the clothes ruined as soon as I start crawling on the floor cleaning up floor tape.