One other thing I forgot to mention: most would-be doctoral students also don't realize that they will almost certainly have to move to get a job.

Most schools have policies against hiring their own graduates directly out of their own programs, and even us interdisciplinary people rarely find a spot in another program within the same university. Not only will you have to move, you also probably won't have a lot of choice about where it is because for the most part, we have to go where there's a job (though with a bit of luck, it seems that most people do manage to satisfy some geographical constraints, e.g. at the regional level.) So if you're unwilling to consider relocating, you really should reconsider the idea of a PhD. Note that it also means that your spouse typically becomes the trailing spouse, and that's something that he should be OK with before you even apply for a program, or it will very likely cause problems later.

IMHO, a PhD should only be done out of passion for research and/or teaching. I get very angry at people who undertake PhDs without that passion, mostly because every admission to a competitive program means someone else didn't get a spot. If they're not passionate about it, the odds that they'll wash out sooner or later are very high.