There are several reasons why SIA has choosen the 777-200ER over the A340-300. Cabin comfort was one of the problems with the A340. When compared to its two stablemates the 747-400 and 777-200 the A340 couldn't compare in terms of height in cabin, lighting and many other small things. Another reason that the A340 is leaving is its speed. Business passengers like yourself like to get there as fast as possible. On flights to Europe, SIA's 747-400s and 777-200ERs arrive 45-1hr earlier than the A340s. Cruise speed, time to altitude and other deficiancies in the A340 program is why they are being disposed of in favor of more 777-200ERs.
"History does not long entrust the care of freedom to the weak or timid." D. Eisenhower