Hard leather?
 

Picked up some of those Meguiar's Gold Class Leather cleaner/conditioning Wipes at AutoZone or was it Peboys? Actually it was Target... anyway...If your seats are getting a litte hard or brittle (see cracked leather) try this:
Before you park the car for the night work the wipes into the leather. Then cover the whole seat bottom with the wipes and let them soak in overnight. The leather is coated but they aren't water proof either. The next morning my leather was extra soft. You'll have to buff out the leather though with a terry cloth because the Meguiar's wipes leave a shiny finish.
Can't beat it for $5.

if it's endorsed by Pefectlap, I just might have to try it!