My husband and I are in our mid-20s and have been married for almost five years. Currently, my husband is finishing his PhD and I'm working, but in the next year we hope to pull off the switch: I'm applying to master's and PhD programs for the coming fall, and he's applying to jobs. Like many who've posted to this thread, we're mostly adhering to a vague plan of applying to opportunities in the same cities and hoping for the best. However, if it doesn't work out--if we're fortunate or unfortunate enough to be offered unparalleled opportunities in two different places--I think we're both committed at this point to doing whatever is best for our professional development. We're ambitious, we don't have kids yet, and we trust each other enough to make it work. What better time will we have to pursue these goals?
I should add that my husband and I have already had the experience of living apart. After I graduated from my bachelor's program, I took a job in another city (I had a service obligation to the US govt) while my husband started his PhD. We saw each other 1-2 times a month, flying between cities on cheap Southwest tickets. The whole situation lasted just over a year. Once I finished my service obligation, I decided that I needed to increase either my professional or my personal level of fulfillment (I wasn't in love with my job). I moved back and found a job in my husband's city. But it was pretty smooth sailing for us the whole time. That is, it wasn't a delight to live apart, but it certainly didn't damage our relationship--in fact, I'm sure it made it stronger--and we'd be willing to do it again if necessary.
That said, the possibility that I could get into a PhD program on one coast while he gets a tenure-track position on the other does frighten me. Committing to a year or two apart is one thing. Committing to five+ years is another. At this point, though, there's not much we can do except sit back and wait for responses. Maybe it'll all work out, and things will be just dandy. If it doesn't and we have a tough decision to make, at least we can make that decision around facts instead of hypotheticals (she says, as if under the impression that this will be a totally level-headed decision-making process...).
Good luck to you all!