David - I'm in the exact same spot as you a couple years down the line. I had to choose between my career or grad school for a PhD in a related field. I chose the field. I've been teaching for about 2 years now, and I'm very glad I did. I've learned so much about the real world - and I continue to do so. I'm in the process of doing the grad apps now, hoping I get in, but the job has allowed me to save up a lot of $$ and to be selective about my grad schools - I have a good job, if I don't get in, I can reapply next year and still have a job.
I don't think I was ready to have a realistic idea of my field and how to without some real field work.
That being said, I have been very clear with my employer about it from the beginning. They've known my intentions since day1 - I haven't advertised it everywhere, but word gets around and I told my superiors directly upfront...Everyone knows now - including clients (ugg). That being said, it's been great to be honest. It's going to be a bit strange if our annual contracts come out before I've heard back from graduate programs, but the honesty is going to give me the space to tell them what's going on. I'm basically going to tell them "If you want me, wait for the apps to come back, if you don't want to wait, replace me." I'm banking on my time and hard work will get them to wait...I think they will - if not, I'll deal and maybe even have time to moderate!
