I'm not sure about the train tour...I haven't heard of that before. Would love to know what it's about, though!
(ETA: Ooooooh, the Magic Behind Our Steam Trains! My mind was stuck in Animal Kingdom LOL -- we're signed up for this tour but haven't done it yet! My opinion is to buy the MBOST tour and just use the night vision goggles at the overlook )
At AKL, there is the Wanyama Safari, which is an evening tour with dinner at Jiko. The tour doesn't visit the park, it's held at the lodge's savannahs. There is also the Night Vision Safari, and that's at the lodge's savannahs, too. AKL also has night vision goggles out at the AKL overlook for anyone to use.
The tour offered that takes place in the park is the Sunrise Safari. This is a pretty awesome tour, but you need to Club Level/DVC to sign up.
If you were planning to spring for an Arusha Savannah view room, I'd look at the cost of Club Level, too...they usually aren't all that different. AKL's Club Level is great, one of the best disney offers. They have fantastic food offerings, including afternoon tea service, and we loved coming back for an afternoon break - we'd head up to lounge for a couple Casa or Tusker beers.
AKL is my one of my favourite resorts -- we'll be back on November 29 and can't wait. We won't be doing any AKL tours, though, since we've had plenty of the "real thing" over the past two years!