I've normally taught Night/Limited Vis, Deep, Nav and Perfect Buoyancy as the "standard" grouping. First off, this really gives a great group of classes to flow together and build on each other. I have also been able to notice a huge improvement in skill as the class progresses. These classes will also help a diver meet most challenges on your average vacation trip. Depending on where I am teaching, I may also add Boat, but that is in addition to the four listed above.
Having worked with both the PADI and SSI systems, I will definitely say that I like the SSI AOW system better. Also, I like how the AOW card shows which specialties were completed for the AOW course. I've had some people ask to have NITROX in the AOW course, but I've never done that, since I've found that most students already have it, so it's normally only one student out of the group that needed it.
Mike