Just did a quick comparison (for a possible upcoming trip).
SFO-PHL round trip:
1. Airfarescout says lowest published fare $278 (no specific dates or airlines).
2. Orbitz gives range of $313 - $404 (various airlines, depart 12/3 return 12/15).
3. UAL.COM gives fare of $232.50 (for a specific pair of UA nonstop flights on 12/3 & 12/15). (NOTE: Today the fare is shown as $379.91.)
4. Travelocity gives range of $249 - $497 (no specific dates, various airlines); gives range of $243.50 to $390.50 on the specific dates I chose (various airlines).
5. The pair of nonstop UA flights priced at $232.50 (now $379.91) by UAL.COM was priced $380 by Orbitz and $420.50 by Travelocity.
Kathy
[This message has been edited by KathyWdrf (edited 11-02-2001).]