Cleaning tan leather seats:

materials:

soft bristle brush (I used a small fingernail brush about 1" by 3")
clean water
Lemon Soft Scrub with Grease Cutter (this product does NOT have bleach)
white cotton towel

drip about 1-2" line of soft scrub on area to be worked.  Dampen brush in water and rub in circular motions over about a 3" by 3" area.  Do this until the foamy solution begins to turn color (off-white).  Wipe the area with a clean part of the towel, rotating the towel to lift the dirty solution off.  Move to another section working the entire seat.  It took me about an hour to do each seat.  On to the pics...

Seat bottom before and after

lower seat pictures without the flash pre and post

seat bolster before and after

Pics of the process