Funny you should mention it... She keeps finding houses in Nortg and South Dakota, Montana and Wyoming... I better pack a bag or she will head off without me pretty quick. Lol.
Which B3s do you have?
It sounds to me like you have gone through the same growing pains as I am currently going through and have finally settled into a set up that works really well for you.
I am definitely not worried about counting inches at this point, I am far too new to be picky. It sure seems like the money spent on a decent set of primary binos goes a long ways across all of the different hunting types and the niceties like 15s or a decent spotter are the icing on the cake. It sounds like you think that decent pair of 8 or 10s and a mid range spotter might cover my bases better for now, is that what you would do in my case?
Do you ever hunt antelope? Do you use your spotter for them if you do? I would imagine you could glass with lower power binos and then get behind the spotter to really pick apart the sage of you think you saw something.
My wife loves antelope and I really love taking her hunting. She was so pumped last year to look at her antelope through her binos before the stalk. Whatever bino / high mag bino/ spotter setup I get myself into will also have to be wife approved (not the cost but that she also gets to use them lol) or she will steal mine anyway