Does anyone have a suggestion on where to find the cheapest tickets to London from San Francisco? I've tried all of the following:

travelocity.com
bizrate.com
british airways.com
cheap tickets.com
priceline.com (but have not place a bid yet)

and many others. The average price I am finding is $550 round trip. Should I be looking for last minute deals or going through a travel agency to beat that price?

You might try www.gotoday.com - www.virginvacations.com - www.gate1travel.com for air/hotel packages.

I got tickets last month on skyauction.com for around 430 rt from Portland, Oregon. It takes a little while and a few tries to get them, but it was worth it.

With sky auction you bid on tickets that can be used during a specific time period (i.e. November & December 1-17 & January 1- the end of March) and then after you have won you request the dates you want. We got our first choice for dates. The "catch" with sky auction is that you need to read all the details on each auction. Pay attention especially to black out dates and taxes & fees that are added.

If you are interested, let me know and I will give you some more tips.

Susan

Virgin has a special on their website from Oct 28--Dec 10th for $209 each way from SF.

If you are willing to change planes in Detroit, Northwest has fares around $415 (incl taxes) for mon, tues, or wed flights.

If you try Yahoo travel (or I assume travelocity, since yahoo is just a front-end for them) and use the "my dates are flexible" option, you can see what is giving lowest standard fares and what days they are available.

As travdog says, Virgin generally have really good deals at that time of year - I've taken advantage of it myself in the past. It's also a great airline.

The last few years I've had better luck directly w/ the airlines' own sites. Sales on VS (Virgin), BA, and AA have all been cheaper than what I could find through travelocity, etc.

Fly BA, Virgin is vile, it's overrated, as are all things under the Branson brand.

While I can't compare the experience to BA as I have never flown with them, we flew Virgin RT from SFO for $350.

Your problem may be the day of the week you want to fly. If you've tried BA's own website then you know there's a function that says + or - a certain number of days to see if there are cheaper options around your preferred date.

You could also try

http://airtravelcenter.com/onetrav.htm
or
http://www.itasoftware.com/
recommended by other Fodorites. I seem to always find the best prices from the airlines themselves.

If you're willing to wait til the last minute, for the last three years we have gotten $300 (or less) fares, including tax on United's website (efares).

Grasshopper:

How long did you wait before you needed to leave to look for last minute deals? I plan to depart anywhere from 9/17 to 9/20.

Are you talking about next year? September is too early for the really cheap fares. I usually pick these up in Nov. and Dec. I look at United efares every Tuesday. They have domestic fares for the next two weekends and International discounts for a little further out (but only about 3 weeks).

US Airways has a San Francisco to London RT airfare for $384. That doesn't include taxes, so add in another $100. Go to www.usairways.com and enter your start and destination airports, then click search by PRICE. You'll see the available December travel dates. USAirways was the cheapest flight to Europe for us last year to Paris. Right now, to Paris is even less than to London!