I've stayed at both, and yes the Sheraton is closer to most of the tourist attractions & Old Town, the newer Westin is in the old Jewish Ghetto (although, from the looks of the area, nothing remains but concrete block apt buildings and newer office towers--that being said, there is the Uprising memorial and the Ghetto memorial nearby). There are a couple of good restaurants nearby and Warsaw is very easy to get around in. I actually preferred the Westin, as it has a more W'ish design aspect to it, whereas the Sheraton is more typical general hotel.