Here are some fares for several destinations that generally would fall within my travel profile (75% work, 25% pleasure). The following represents the fare increase from lowest US Airways website (Travelocity) discount fare to the first qualifying fare. This is the increase necessary in order to obtain tier miles. Feel free to add a few flights from your travel pattern.

Obviously, US Airways could not implement this policy in a vacuum. The agent I spoke with today related what others have noted--the other majors will follow.

BOS-ORD $168 V $418 M 148%
BOS-SJU $279 V $1316 A 371%
BOS-SEA $248 K $462 M 86%
BOS-DCA $169 V $198 U 17%
BOS-LAX $395 H $499 M 26%
BOS-LGW $366 Q $600 M 63%