Is this flight info hogwash?

Well...looking further it is just one flight I see is filling up. That is LHR to IAD after leaving from Athens.

Do you think it the model seating is correct? Do you know if they add flights for the same time and route if a plane fills? I'm not sure if I should pull the plug and buy now, the price just seems way too high for most flights these days. If is was $1500 I'd understand. Eh...what to do?

Have you tried searching for flights out of San Francisco instead? It's more of a hub and the prices may be better...a little further for you to go but it might save you quite a bit.

Impossible to answer your questions since you have provided so little detail. Some general points...

Buying airline tickets is a crazy complex stew filled with options. If al you are doing is trying one search on one website, you haven't even begun to start. There are endless options out there.
Flying in/out of a small market (eg Sacramento) will tremendously limit your options. Look for flights between major gateways (for you, San Francisco or Oakland), and then worry about getting from your home to that gateway. At least explore those options.
$1700 round-trip from a small west coast city (Sacramento) to Europe and back is not necessarily outrageous - although I bet you can do better if you invest a little time and effort. July-August is peak season for Europe.
Airlines constantly adjust their schedules, although most major airlines are not in the habit of adding extra flights on routes just because their planes are filling up. They work hard to keep their planes full - thats how they make money - so adding another plane in order to reduce crowding on existing flights is not exactly in their best interest and I wouldn't count on that.
Are you going out of your way to "pick up" someone in DC? That's an extra stop which is going to limit your options. What happens if you don't try to do that? Can't you meet your sister in BCN?
Note that what you see online are not tickets sold, those are seats that have been claimed - there are more tickets sold where people do not yet have assigned seats. If you are only seeing a small number of unassigned seats on a flight, then it is actually more crowded than it appears. The demand (number of seats sold) drives up the price for the remaining seats.
How many stops are you going to subject yourself to? SAC-SFO-IAD-LHR-BCN? Yikes, sounds miserable, it'll take you 2 days to get there.
I'd invest a little more time in searching for better options (and by "better" I don't just mean price - I mean a reasonable routing with minimal connections at convenient times, in a seat that has not been squeezed).

Great advice from Anita & David

I searched flights using google.com/ flights, departing from San Francisco, and found some flights for around $ 1,500.

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Good luck!

Also, break it up. Fly Southwest, or another airline if you get a better price, to and from DC, stay the night and find your flights from there. Look at intra-European flights from Athens to Barcelona and do a Barcelona round trip from DC. Look at all three DC airports, not just IAD. You need to put it together like puzzle pieces. And drive to SFO as others have suggested, or SFO and Oakland if looking at Southwest to get to the east coast.

Example: if I fly from my home airport, IND, it's 1,200 rt to Paris. If I take a $69 flight to Chicago on United, the rt to Paris is between 500- 700. And thank you Norm and Jean-Paul in Indianapolis for the airfare tip!

Thanks for the feedback. We don't have to "pick up" my sister and could go another route, but actually out of Sacto it is a decent flight with only one stop in DC to Barcelona. Dad and I decided it isn't worth the savings flying out of SFO since it is a 3 hours, maybe more with traffic, and would need a ride each way- miserable for the driver! I know we could get cheaper with options you have all given, (thanks for the tips) but simplicity is better for dad, and he would enjoy being with both daughters on the way over. We are catching a cruise so we have limitations with our schedule for getting there.

Interesting that flight might be more full than it shows. Makes sense! I've tracked flights for years and just haven't seen them this high so I hesitate to jump yet. Maybe I'll give it a few weeks and see what happens. We could always fly without sis, but those routes I found seem to be the most decent, too. Coming home from Athens we fly to London and then DC to Sacto. Not great, but seems out of Athens is more challenging getting a decent flight. Although, of course to SFO it would be better. Decisions, decisions....

Thanks!

I tend to buy the flight I want versus the price I want...if I can't find the price I want for the flight. If you want to travel with your sister, then I suggest you bite the bullet and buy the tickets. It is more important to have a good time than $200.00 saved a piece, IMO.

Yes, I think you are right. If it were $1500 I'd say it was about right, but it really is only $200 more dollars each for me and dad, and he is paying! I'm just so cheap and of course always looking for deals. There have been great sales lately and even though our preferred route might not be one of those I'm still suprise do to see it so high. But again, dad likely cares more about being with his daughters than $400.

Thanks!

I've found the United website to be very accurate regarding seat availability. What I have seen prebooking was the same as when I went to book. I understand your reluctance to book. That does sound kind of high. I would probably wait it out and monitor the fare for a month or two. FWIW, That fare is more than RT SFO to London in premium economy, but that's for shoulder season not peak summer.