The S3 is a big phone, it's kind of comical looking, at least to me, in terms of its width, its extremely light weight and how its framed by plastic, along with Touchwiz and the hardware buttons all the way at the bottom. I bought a MAXX HD a week ago and love it. I came from a Thunderbolt, which I wanted to run over with my car time and time again. The biggest problem with the Thunderbolt (and with my current laptop) has been battery life, so that was, is, and will likely always will be, my top priority
Your wife likely has smaller hands than you. But the fact that she has mentioned the Note makes me think she doesn't care much about one-handed use. I would say this about the size comparison: Even though the MAXX screen is 4.7 inches, because of the on-screen buttons, the amount of always usable screen space is actually very comparable to the Thunderbolt, which made for a very easy transition. Even though I suppose I have larger than average hands, I didn't want a phone with a 4.8 inch overly wide screen plus hardware buttons; it's simply too large for easy use in my opinion.
Plenty of people would disagree with me, though, as there are a ton more people who have an S3 than the MAXX HD, and people will probably continue to buy the S3 in much larger quantities, even on Verizon. I wanted to like the S3. I wanted to convince myself to buy the S3. I made an effort to try to buy the "popular" phone, since I feel like I've gotten burned in the past by buying otherwise (HTC Tilt, Touch Pro2, and then the Thunderbolt), but Touchwiz, the S3s size and the build quality, along with an unimpressive battery, turned me away. I'm very happy with my MAXX. Does it lag occasionally? Once in a while, but Jelly Bean should make things smoother. Will I ever be able to root it? Probably not, but I never rooted by Thunderbolt. All I know is that the security I feel with knowing that no matter how much I use the phone -- no matter how many widgets I run, how bright the screen is, how many programs are running in the background, whether LTE is on all the time, or how often I sync my email -- its battery will never die is absolutely priceless. If your battery is dead, it doesn't matter what phone you have. If you're turning off LTE, not syncing your email as much as you want, limiting the number of widgets you use because you're worried about your battery, why even bother when there's an alternative?