Here's a recap of the point situation.
NOW: Rafa 9760, Roger 9605 (Rafa +155)
Rotterdam (Feb 12): Neither played last year, so no points to defend. If Roger reaches the SF he gets 180 points and is ATP #1 on Feb 19 (+25 points over Rafa). If he reaches the final he's +145, if he wins it he's +345. He'd be #1 at least for two weeks, until the week after Acapulco/Dubai - and maybe longer.
Acapulco/Dubai (Feb 26): Rafa loses 300 points, while Roger loses 45. If Roger wasn't to play Rotterdam, that would put them at 9460 Rafa, 9560 Roger - with Roger up by 100 points. But Roger is playing Rotterdam, so any points there will only add to his lead. He could be anywhere from 120 to 600 points ahead. In other words, if he wins Rotterdam then Rafa can't retake #1 until Indian Wells.
Roger has to let Dubai know if he'll take a wildcard by Feb 19; the Rotterdam final is on the 18th. So I think his decision will be based upon how he feels on the night of his last match at Rotterdam, whether that is early or after the final.