They chose to go dark right at the hand-off point between Malaysian ATC and Vietnamese, maximizing the time before they would be missed. Then they turned west to minimize tracking by military radar. Then probably northwest towards a destination somewhere in the 'stans.
There remains the problem of Indian and other military radar along the way. How do they react to non-transponding blips? Perhaps, Captain Zaharie tail-gated a legitimate flight for a ways. ATC would see the legitimate flight's squawk. Military radar would see the legitimate squawk along with a slightly brighter blip?
Did you already see the possible wreckage and debris on this thread?
http://www.freerepublic.com/focus/news/3133830/posts?page=65
I just read this and it was news to me:
the flight not only made a total U-turn from its planned route but also dipped in between radar points for hours and had all of its tracking systems manually turned off.
http://www.freerepublic.com/focus/f-news/3133972/posts
I heard on CNN that Pakistan had a radar problem. Possibly to cover up the real story. They allowed MH370 to land.