Is that $600 including tax? Sounds pretty excellent if so. What airline and schedule? I wouldn’t recommend using name your own price on Priceline generally for flights, because it’s completely inflexible when it comes to any changes.

Yeah, if you found $600 round trip, tax included, that’s very good for September from Seattle, and you should book it. Cheapest I see from ITA is $801 in Sept.—to Glasgow.

Also try www.travelteam.com

The $600 is before taxes. 
 
It seems like most of the sites where I’ve been don’t show the taxes until you go to shopping cart.
 
Looking closer that fare adds over $300 in taxes.
 
Yet one more complication…

I’m usually keen to adjust my itinerary to the cheapest flights, but in your case what cities are you hoping to visit?
And what are your dates of travel?
That will help with figuring out what to suggest.

In addition to Travelteam, be sure to try the links, tips, and strategies in our “New User” thread, top of this forum.

We are going to be travelling around mainland Europe – mostly concentrating on France and Italy – possibly also Greece and maybe a little bit of Spain or elsewhere (Germany? Prague?).
 
I don’t want to be too whirlwind, but we probably won’t have another chance to go to Europe for quite some time (15 years?)…
 
It seems like Paris is probably my best option for making a loop – but maybe Athens or Zurich would work as well – or even someplace in Italy.
 

If you don’t mind a layover, I just got my ticket from Seattle to London on August 22nd for 819.19 after fees and taxes through Air Canada.  It’s like an hour stop in Torronto or something.  I was pretty happy with it!

Thanks everyone.
 
I found a direct flight to Paris on Zoom airlines out of Vancouver, Canada for about $784/ea (after taxes and exchange rate fees).
 
Yay!