Hi!
I like the Idea of suffering "bad conditions" from a fall very much. Dazed, stunned, incapacitated would propably fit, and it could be avoided by a Fort-Save. As DC I'd suggest 30 + 1 for each 10 ft. of falling to avoid becoming dazed, 20 + 1/10ft for stunned and 10 + 1/10ft. for...