A similar thread is running on The High Road.
http://www.thehighroad.org/showthread.php?t=179163
While most people think the .243 is adequate, since its introduction a number of cartridges have been introduced or "rediscovered" that provide more potential, including the .260, 7mm-08, 6.5x55 and .257 Roberts. If you load your own you easily can tailor loads that approximate the recoil of the .243 while preserving the ability to upgrade without acquiring another rifle.
Recoil also is a function of gun fit, recoil pad and maybe even a shoulder recoil shield. A .30-30 with a hard plate may feel worse than a well fitting .260 with a Decelerator pad or Limbsaver and a shoulder worn PAST recoil shield.
Before you run out and buy a Browning, I think you should take her shopping and see what fits her well.