Hi again all-
Thanks much for all the great input. Since there was a direct question to me I thought I'd address this first...
What about the AR-15 your wife fired did she like about it? It seems like you and she want a fairly simple / basic rifle or carbine for range use, but I don't want to assume anything.
Actually, I never saw it. We were at the local indoor range with the kids; I had our girls on one bay and she had our boy in the other. Somebody in the bay next to her asked if she wanted to try one; I didn't hear about it until we'd left the range. She said she liked it and could see why people would want one. As mentioned above, they've not necessarily been my thing but since she's intrigued I figured now is a good time to figure this out (as opposed to when something happens and everybody panics).
So in essence, the assumption is pretty much right - I could see getting more serious than range/field, but for home defense it's a bit much - given the layout of our house a handgun (easily locked when not in use) or a shotgun (preferred, but less easily lockable). If things ever got where it would need serious SHTF use there are a lot more problems than currently anticipated. Hence, simple, basic, works, allows us to learn the platform and identify what we might really want - these are the goals.
Good to hear about the Core15. I'm not locked in at all, but I kept seeing prices that were in the pretty low range ($650 for a new one with chrome-lined barrel), and the reviews I had seen (albeit not of the particular model I'm curious about) were favorable. This said, I may have come across a less expensive option that allows me to ease into things (see below).
On Adams, I've noted that some mentioned issues, but I've also noted that Palmetto State Armory sells Adams uppers so they must have some degree of quality.
Over this weekend past a friend mentioned that he's got a stripped PSA lower he'll sell to me cheaply and he's built more than a few of these. That plus one of the good kits that PSA has (not right now - it appears that everything is sold out) may put us at a good starting point. For sights, I noticed that somebody's selling some pieces off a S&W for $65 which includes both the front and rear sights (if I'm right on this - rear one that mounts to the rail and front one that mounts to a rail on the gas block - if not I'll get some more advice). Short term iron sights to get used to things - later a good red dot either with flip-downs or to co-witness.
There is no huge imperative right now - the more I learn the more I realize two things - I still need to learn more but that putting one together is pretty straightforward - I am reasonably mechanical and have done fairly simple things like replaced internal parts in a 10/22, and can field strip anything I own. Hence, with the range of "how to build your AR" videos online and a good resource nearby I feel reasonably comfortable and that's where I'm leaning.
Again I thank all respondents - you have added greatly to my knowledge.