It is a simple decision: nice but far away (JW Marriott), close but nowhere near as nice (HGI, or Hilton even).
But when I was looking at hotels I found out that all the really nice hotels aren't in Old Quarters anyway (well, I'm not sure of the actual definition of Old Quarters. I define it as north of Hoan Kiem Lake)
If you are in the town though (not in West Hanoi) and don't feel like walking the requisite 30 minutes to get places you can easily take a taxi for a few dollars.