Without ever being there I would probably agree with LM Sentral for convenience and such.........We just thought for the first night we would try something different since we will be at the LM for 3 nights on the way back.
We will be exhausted so it will be just as easy to jump in a cab to LM Putrajaya (and probably get a 30 minute nap in!)

When we return we will be out / about and such and I see you mention the Sheraton Imperial at a better location - I would hazard to guess we will be fine at the LM Sentral as it looks like a much nicer hotel. We don't mind doing a little walking or whatever it takes as it just adds to the experience.