Go for it.
Running the nook color with CM7 from a SD card will be great for you and a NST (maybe the new GloLite model) will be great for your wife.
Thinking further, your intended uses for the nook color might be satisfied with the stock B&N OS. What will the CM7 or other Android do for you that that B&N won't do right now?
And before buying a NST for your wife, check to see if she'll use it. If she's not using her nook color now, will she use a NST as a replacement?
Thanks for the feedback. Honestly, I'm not sure how much I'd use the full Android side, but mostly want to do it because I like tinkering with things (I work in the tech field). That being said, I'll probably try the stock side first and see how that goes.
I need to get her the e-ink becuase that's the deal I made with her in order for her to give me the color :-)
I use the stock Nook Color to surf the web and check my email with no problems. Unless you have specific Apps you want to install I see no need for the card except to satify your tinkering itch. That's probalby as good a reason as any.
NC performance is more than adquate for the sort of casual usage you're describing, even at stock. I even find it fine for watching video within the limits of the device. NetFlix, HBO Go and Max Go work well enough to watch. Network bandwidth affects video quality more than anything. Even some fairly sophisticated games work smoothly.
If you do either root the B&N firmware, or boot alternate firmware, you have options to increase the clock speed up to 1.2 GHz as needed. As important -- at least to me -- is the additional control you gain to underclock and/or undervolt to further improve battery life.
Since you've already got the NC in hand, there's no price comparison to be done. If the lack of GPS, camera and bluetooth don't bother you, then it is an excellent basic tablet. I consider it 80% of an iPad for a fraction of the price.
At one point, I was using only the n2a side of my NC as I had my nook app, my kindle app, etc. HOWEVER...Whenever I was reading on the Nook app on the android side, it never went to sleep. All the other programs went to sleep, but not the Nook app. I could not find any settings in the Nook app to make it go to sleep too. My battery was lasting 2-3 hours max if I had the Nook app open. I realize that I could just close the app every time, but I didn't remember to do that all the time and I just got tired of it of my dead NC.Luckily, I could read on my NST while is was charging but what a PITA.
Now I ALWAYS read my nookbooks on the stock side, and only use the n2a card for non nookbook activities. It IS a hassle to always have to reboot to go from one OS to the other.
I've rooted my NST and I like not having to reboot all the time, just hit my N button and I can choose which "desktop" and there it is without rebooting. I'm seriously considering doing the same to my NC but haven't got to it yet.
Quite honestly, I think the Nook Color would be perfect for what you want--without the Android card. I did get the N2A card, but I rarely use it--mostly when we're on vacation because it has a good crossword app and I can still do my morning NY Times puzzzle. Occasionally I use it when a library book in more readily available in Kindle format. I much prefer the native Nook interface for reading. The web browser available on Androis is marginally better than the native one, but for casual browsing, there's not that much difference.
That being said, an Android card isn't that expensive whether you make or buy it, and it does give you ore options. Either way, I think the NC would suit your needs just fine.