As a former .257Roberts owner (ruger M77), I must say I prefer and reccommend the .25-06. Recoil difference is not noticible (and I'm admittedly very recoil sensitive) More factory load options, gun options, and re-sale options for the .25-06, along with a slight increase in power. Buy her a .25 -06 in a savage and you won't look back.
Unless you reload....then the .257 is pretty darngood.