As good as these things are to many (most?) people, I have heard some folks regret and sometimes even uninstall armor, LSDs, autolockers in the rear, and even regearing (or at least the particular gearing they chose the first time).
But I have never heard anyone regret installing a selectable locker in the front or rear, in any context. And I have never heard anyone with tires 33" or less regret installing the Superior Super 35 kit in order to run a Dana 35 with a locker in the rear (on this forum ... but this forum is the only place I've read about Super 35s at all).
Given that the OP says he really likes running with open diffs some of the time and he's an East Coaster who is unlikely to see crazy rocks, or at least ought to wheel for a while before he attempts them, that makes me think he should probably install a selectable locker first. I hate to say this because in my view the best bang for the buck is an auto in the front and an LSD in the rear, but for OP it sounds like he's going to be happier with the selectable, and he can get to gears and armor later if he decides he needs them, and he'll definitely have a more refined idea of what he wants (tire size, gear ratios, armor needs) if he waits a while on those items.
The only problem is that if he gets the selectable professionally installed, it would be most cost effective to do the regear at the same time, which isn't the way the OP set up the original question. (Works in the other direction, too ... if he decides to regear, it's more cost effective to do lockers at the same time ....) This is the kind of thing that drives you nuts when you start messing with your axles.
Makes my head hurt just thinking about it, which is one of the reasons I stayed with 31" tires, my stock 3.73 gears, and a DIY auto front/LSD rear install. (My wallet thanks me.)