Lyn here from firsttimesecondtime (thanks for the shout out osker!).
Escher -- you are really smart to think about this now. I know you said that maybe it doesn't really matter, but honestly, I think it really can, depending on the structure you'd like to have for your family down the line. This choice is a place where we have options that a straight family doesn't, and it is possible to leverage that. I'm going to assume you are both perfectly fertile in what follows (which is a HUGE assumption).
We made a lot of our decisions on accident, but they turned out to be really good ones, which we can see clearly now. In our case, we both wanted very much to birth a child, but my wife was 6 1/2 years older and was mid-30s, so she got dibs on birthing our first (our daughter, now three). In the plan from the beginning, though, was that I would carry our second (which actually worked, our son, now 3 months).
Carrying, birthing and nursing a baby is hard. But don't underestimate how hard it is to be a non-bio-mom in this context. There is little or no social support, and it is really confusing to try to find your footing as a parent when there are no (or very few) maps out there (and frankly, much of what is available tells you to step aside, and be more of a back-up mom or a proto-dad -- which would NOT have worked for us). It can be hard to even figure out what is so hard about it! Because of this, it ended up being great that I was "non-bio" first, because I am extremely communicative and good at noticing and figuring out what is bothering me. This ended up being a big perk, because we were able to work through lots of our possible problems before our daughter even arrived, problems we wouldn't have noticed if I hadn't seen them and spoken up. So, does one of you have a particular knack for noticing and communicating hard stuff? If so, she might be a good candidate for non-bio-mom-hood on the first go. More about this here:
http://firsttimesecondtime.blogspot....nowing-it.html
I also often suggest that folks seriously consider having whoever wants a child *less* and/or cares *less* about getting pregnant/birthing get pregnant first (though I can't say anyone ever listens to me!). Paradoxically, it can be good to have the more motivated party in the non-bio role. Carrying, birthing and nursing an infant will pull whoever is pregnant into a caretaking role, whether she is really into it or not. But a non-bio-mom who wants a strong relationship with her kid(s) needs to really get in there. She needs to be really excited to take care of her baby and spend the time building the relationship, excited enough to do it without much (if any) social support. In our case, this ended up sort of also being true, because I am very much a "baby" person. My wife is less so, and it has been a little hard for her with our second, because she has to, as she says "choose" to care for him. It doesn't happen automatically.
It can also be good to consider economics, and it can be good for the parent with *more* economic power (i.e. who earns more or has more earning potential down the line) to birth, or birth first. In this case, then, there is a biological pull for one mom towards caretaking, and an economic pull for the other (if/when a career sacrifice needs to be made to prioritize caretaking, it is more likely to be made by the parent with less economic resources). Again, this was true for us, completely by accident, but ended up really helping us balance out our parental roles and come to a good place as a family. I wrote more about this here:
http://firsttimesecondtime.blogspot....nowing-it.html
Also, your idea to have one mom birth and the other home is a good one. There is nothing better than time with your kid to build a solid relationship, and that time is particularly important for a non-birthing parent (dads too). We think it's important enough that my wife is actually taking *more* leave than I am to be with our second during his first year. Similarly, I did a bit more care for our daughter her first year (though it was by "accident", due to the economic pressures mentioned above).
Two more things:
1) I highly recommend each taking a "turn" birthing as it were, but it is not without emotional hurdles of all sorts. IF this is part of the plan, I'd encourage you to think hard about setting up plans for number two. I.e. make sure you both have a strong commitment to making it happen and consider making sure you have sperm from the same donor available for the second (either a commitment from the KD -- assuming it's not the brother -- or vials on ice). It is amazing the number of pressures that conspire to make that second pregnancy disappear, so if it's important to whichever of you doesn't carry the first, do hash out a plan ahead of time. More about this here:
http://firsttimesecondtime.blogspot....witcheroo.html
2) We are both nursing our second, and I see the suggestion thrown around quite commonly, but as far as I can tell, we're the only family with much of an online presence who has actually done it. (Please! MDC prove me wrong! We would LOVE to find another two-mom family in which one mom birthed and the second induced lactation for nutritive nursing--i.e. not a two-mom adoptive family, and not one where one mom was still nursing a toddler and just kept going (Hi Lex!). PM me if you are in one or know of one!). There's a good reason for that. It is extremely hard. We've detailed the experience on our blog, but long story short, there are very few families I would suggest it to, and though we're enjoying it now, the experience has erased any regrets I may have had about not inducing lactation for our first. Really, as a first time parent, it would have been extremely hard. It's extremely hard to get full supply, or even enough supply for a reasonable feeding or two, and there is your wife, with milk flowing like crazy. It can put you into kind of unfortunate competition, and take time *away* from spending time with the baby for the non-bio-mom (because she's so busy taking a million herbs and pumping desperately). If anyone asked me (not that you did!), I'd strongly suggest comfort nursing and expressed BM bottles for a non-bio-mom on the first go over an induction protocol. For a second child in the case of a "uterus switch", I'd say it's only a good idea of the parent carrying the child is very comfortable with. This was true for us, and seriously, if I were not extremely supportive of Gail's nursing our son, I could have thwarted her in about a million ways without even knowing it very very easily.
Good luck!
Lyn