Speaking of the wife, make sure the stock fits. Much more important than the exact chambering in a group of similar. Mine has shot a Browning A-Bolt Micro for about 20 years now. It's in 7mm-08 and fits. I load low range loads with the 120 Ballistic Tip and she's happy. Buck she shot last year was about 20 yds and he was never out of the field of view from shot to drop. Could have used a .260, or .308, or some other. Low Recoil loads are available in a variety of rounds if you do not load.

For you, NEED has no relevance in discussing the acquirement of an additional rifle. But since you laid the guidelines I'd add something fairly common but still a step up from the 6.5 . Probably 30-06. As far as deer hunting I view it as a "magnum" since the cartridges mentioned above do as good a job with less fuss and flame. It's a friggin hammer on deer with 150 grain bullets I know for a fact. Never shot an elk but expect one couldn't live through solid contact with an appropriate bullet from one.

And speaking of the wife, make sure the stock fits. You'll come to enjoy her success more than your own. Good luck.

“When Tyranny becomes Law, Rebellion becomes Duty”

Colossians 3:17 (New King James Version)
"And whatever you do in word or deed, do all in the name of the Lord Jesus, giving thanks to God the Father through Him."