What you are asking is very hard for someone to answer for you. There are a lot of variables that would influence what "best" might be.

Some people love beach/ocean locations, some prefer skiing, some local history sites, some access to social gatherings, even others want access to great sporting events. Where have you been in the past? Where have you always desired to go but never been? Are you talking about Marriott Resorts only? What about Ritz Carlton hotels? (They cost more points, but can be very very nice.) Would you be traveling alone, with a spouse or significant other, with kids or other family members? Do you want romantic? The more info you give us into what your looking for the better able we can help out.

Also, there are a number of threads about hotels in a lot of cities and countries. If you have a specific country/city you would like to travel to, try doing a search for it and see what comes up (i.e. a search for London will bring up a lot of threads on the best London properties.)