Thanks for your reply

I appreciate the information.
Re: your question about my son's age, he is 21 months. I expected that it would be rough for me at work for a year or so after he was born and then get easier as he got older, but so far that hasn't been the case. I feel like I've missed out on a lot of time with him, and I'm very aware the the years are ticking away until he'll be in school, and I really don't want to miss any more of this precious time. Plus we want at least one more child and I imagine I'll feel the same way with them. I think I'm just different from most of the women in medicine I know...quite a few of them have expressed to me how happy they were to go back to work after their babies were born "to get a break" from the baby and I couldn't feel more the opposite way. I don't think they're wrong for feeling that way, but it couldn't be further from how I feel. I feel almost like I'm a different person since my son was born and the things that were really important to me before, just aren't as important anymore. What I really want is to be home. I want to work enough to preserve my ability to get back to clinical work full-time when my kids are older, but that's about it. If I could swing 20 hours a week, that would be GREAT in my book.
I'm just not sure how part-time it is possible to be as a physician...everything that I find about working part-time is talking about 30+ hours a week, and at that level I'm not sure the trade off is worth it to me. I mostly like the work I'm doing now (research), I just don't like how much I'm doing it (averaging around 40 hours a week, though don't know how sustainable that is...may go up in the future). If quitting my job and going to part-time clinical work is still going to mean 3 long 10-12 hour days a week, I'm not sure that's a huge improvement over my current situation, especially if I like the work less.
I realize I probably sound like I'm complaining and that many women doctors would KILL to be in my position, working 40 hours a week...but nonetheless, this isn't really working for me and I want to look at my alternatives.
Re: Kaiser, I thought of that as an option because my stepmom is a Kaiser doc (in Colorado) and she says lots of women in her department work 0.6 or 0.8 FTE...so I thought it was a common arrangement there. I'm not saying the jobs are easy to get, but if you get them I think they're pretty amenable to part-time. Probably varies based on specialty and location, though.