I did my ATP back in 2001 with the Richmond, VA ALL ATPs. I already had my written done, but I hear their test prep is well worth it. My flight training was in a Seminole, I rode along with an MEI student and Commercial - multi student. It was pretty straight forward, pretty much just an instrument rating ride. I did one training flight and then flew everyone to RWI for the checkrides. I think it was maybe 3 hours of flight training. They prep you for what you need to know for the checkride.
PJ