Congrats, wonderland! Now, why don't you start giving *us* suggestions about how you have been so successful!!! ; )
Hi Heronhouse. Sorry for the delay because I have been trying to tie together the loose ends of the offer. I am not sure to what extent our situation has relevance to others with two-body problems, because we feel extremely lucky that the schools we have dealt with this year are very (or perhapas unusually) generous and accommodating (given that this is my first time on the market in the Humanities). But just in case it may be helpful to anyone at all, I will share some of our experience or thoughts here.
In a nutshell, one of my offers has a institutionalized policy of providing a fix-term position for a new hire's SO (for a few years at most). This created enough pressure for the other school to search for more attractive deal, and thus a tt for my SO within two weeks, and this in turn encouraged the first school to go for a tt as well. The fact that my SO already holds a great tt position significantly helped in this situation in demonstrating SO's qualification for such a position at the new school.
What we have learned from this case are as follows (of course partly based on some inferrences): (1) In order to create a SO, it might be crucial to have at least two offers; (2) both schools are genuinely interested in getting you (presumably, you are not only the first choice at both schools but also have substantial edges over the next candidate); (3) the two offers are comparable in academic standing and but have DiFFERENT/comparative advantages, so both might have the incentive to "outbid" the other by accomodating the SO as an additional edge; (4) if one of the schools has regularly offered some accommodation for a new hire's SO (even if not a tt position), this might serve as a good start for the negotiation to proceed; (5) another important thing is to have patient and nice Chairs and Deans to work with throughout the whole process at both schools, so that at least one of the schools will create a tt (hopefully) for the SO. (Even if we had to make a choice btw the schools, we really admired and will remain gratefuly to the Chair and Dean of the school that we won't join for their accommodation and patience).
Some of this might sound like a matter of pure luck, but it also takes the initiate and efforts to work the whole thing out. Above all, one also needs to handle the negotiation professionally and in good faith, since it is not easy for all parties involved in this process. Either way, as job candidates, we (at least I) should be thankful to the schools and administrators who were willing to seriously explore the possibility of a spousal hire, even though they might not always be successful, due to institutional culture, budgetary restraint, and so on. Best of luck to all.