You should buy the 80mm, since I won't be packing it or paying for it, but would get to stick with my 50mm and rely on you to check over anything it wouldn't.
It's only money....I'm sure the you wife won't mind as long as she doesn't know how much it cost! And don't tell her it was my idea either!
I'm using the Swaro CT 30 x 75 and it's been a good trade off for weight and bigger objective. Of course it's not a variable power scope, but it gets the job done and much cheaper than the really big glass. I did a review on it, we just haven't got it uploaded yet.
It's worth it to me to pack the extra weight, but most guys run a 65 or less for backpack hunts.
I can tell you that you'll be packing the better part of 6 lbs with a 80/85 spotter and tripod.
My 85mm Zeiss, spotting scope, 75X eye piece and Outdoorsman tripod weigh 7 lbs, but I'm happy packed it when the glassing starts.
For me it really depends on what you are hunting and how far back you are packing. If only going in 5-7 miles and then climbing 3000' and hunting deer which are often a first/last light sort of deal then I'd opt of the 80mm class. If you are like me and have 20+ mile approaches for sheep and then go up 3000' I opted for the smaller lighter 65mm. Personally, I wouldn't own a 65mm if it didn't go to 60X though. I had a Ziess Diascope that had the 15-45X and compared it to my buddies 65mm Swaro and if the conditions allow the 60X is way nice. Needless to say I picked up a 65mm HD spotter the next year.
For just straight glassing though, nothing is gonna beat that Hubble Aron hauls around. The one I looked through was a joy to glass with. Though still not worth the additional 1.5 pounds for me at least when I sheep hunt primarily with my wife so every pound counts.
I wrote of an article that might be worth reading for ya as well:
That could work since your gonna be carrying the tent.
She knows what all my toys cost....doesn't seem to mind. I think she thinks of it as a backup retirement plan.