Best stuff for the leather is Gliptones Liquid Leather. As well as treating the leather, it makes the car interior smell like a Bently - lovely stuff. I even keep the duster I use to apply it in the door bin, as the duster smells so nice.
I get mine direct from Gliptones via mail order here:
http://www.liquidleather.com/index.htm
Hope this helps,
Cliff