A new gun for your wife eh? Ok, if thats what you say...lol.
Well I've never been a fan of the .308 even though I owned three of them. I used the .243 for many years and took alot of whitetail with that rifle using 100 gr Hornady bullets over 40.5 grs of IMR 4350 and all but one dropped where they stood. I also own a Browning Micro Hunter in 7-08 which I really like. Its easy to tote around in the woods, recoil is just slightly more than the .243 and packs a bit more punch. I load this cal with 150 gr Rem core lock bullets over 46 gr of IMR4350 and took a nice whitetail this year with it.
My opinion, buy your wife the 7-08. If you look around I think Remington makes its Model 7 in a youth model that should fit your wife better than a full size rifle. And as long as we're on the subject, what about the .260 rem??