The Announcements page for each hotel should include a Resort Fee notice, if they have one. You should find the link to Announcements at the top of each hotel's webpage near the address and phone number. You may also find links to the Announcements during the reservations process. Unfortunately, every single Starwood hotel seems to have an announcement of some sort now, so the page exists even if it has nothing to do with otherwise-undisclosed fees. The "Special Conditions" links during the reservations process do not necessarily include information about resort fees.

It does seem that Starwood is doing a better job about getting the resort charges into the rate "Terms & Details" section during the reservations process. Does anyone have some examples where it currently does not?

To add to my earlier comment about taxes on resort fees, here's an example:
At the Westin Savannah, the resort fee is $19. To this, they add Georgia State Sales Tax (7%) for a total of $20.33. If the same revenue of $19 were instead included in the room rate, then it would also be subject to the 6% local tax for a total of $21.47.