Here is a thought, why not rent some lenses to see if you enjoy it before purchasing it?
Also, having different lenses will allow you to have more variety in your shots than just having two of the exact same lenses. Since you will be together, you might enjoy swapping lenses at times to get a different perspective.
Also, since this camera will be for your wife, would she appreciate something a little smaller than the 60D, such as the 600D (T3i) or the newer 650D (T4i)?
You also said that you enjoy the outdoors, so if she would like more of an all in one solution, there is the Canon EF-S 18-200mm
as well as a Tamron 18-270mm.