Well.. flightnetwork.ca will pull up Tango fares first, but readily displays the fares for Flex, Latitude, Business class (Lowest), and Business Class (Flexible).

My favorite thing about the website though, and what makes it the primary site I use to book airfare now, is that their price drop guarantee is (from what I've seen at least) is amongst the best in the industry. Orbitz will give you a credit if someone else books the lower fare on the same flight. But Flightnetwork will let you "claim" the price difference, and then issue you a credit to use on a future flight. And it acts just like a credit should, so if the fare that you used the credit on has a price drop after you've booked, you can claim the difference on that one too.

Only catch is, you can only claim the difference once on each booking, so choose wisely!