I try to figure out the "opportunity cost" of using points by equating the "cash value" of those points to a higher category room. For example, in the future, if you are planning on an overnight stay at, let's say, the Sheraton Towers-Chicago for $135 per night (Category 4), your 2000 points for $62 per night looks like a great deal - whereas, if you are planning on staying at, let's say, the Westin Maui for $350 per night (Category 4 also), your 2000 points for $62 per night is not as good of a deal.

In addition, like the previous posts explain, you also need to figure out how many Starpoints you could earn by paying for that stay. For example, I stayed at a Four Points (Category 1) this past June and chose to pay for one night since I was able to earn enough Starpoints to almost cover a free night at a that hotel (approx. 250 gold SPG stay + 1000 web booking bonus + 500 AMEX stay bonus + 90 charged to my Starwood AMEX) plus this gave me my fifth night at a Starwood hotel which earned me two Free Fridays!!