a paler version of the exact same sage on the top half? Or are you set on half being white? Putting the darker shade on the bottom seems like it would be easier to keep the wall looking clean and putting the paler shade on top would reflect light more and make the room feel lighter and bigger. But white and sage could work too. I love sage green, however you decide to use it.
I'm not set on anything, lol. I've had a dark-ish sage green living/dining/hallway for the past 18 years, it will feel weird to not have a sage green room!