Flying Open Jaw

Doesn't sound like you did anything wrong. Sometimes combining one round trip and a bunch of cheapies comes out better. I did the same last spring for a trip to Spain -- round trip to London, then took Ryanair and Easyjet.

You really never know. I don't buy plane tickets until I check out numerous aggregator search sites (kayak.com sidestep.com farechase.com mobissimo.com) and airline sites, pricing all kinds of options and city pairs.

I mostly have done the round trip from London and headed out from there on low cost carriers or trains / ferries. Last year though, I was able to find tickets using sidestep.com (which found the airfare at united.com and orbitz.com) from Phoenix to Frankfurt and return London to Phoenix, both via Chicago. The Frankfurt flight was codeshared on Lufthansa. It would have cost more to do round trip from London or Frankfurt.

Are you sure you were using the search engine properly/ Entering multi-cities and not a series of one way tickets. This past summer it was 100 dollars cheaper for us to fly into Rome and home from Zurich rather than round trip to Rome. I recently price a London/Paris for some friends and it was only 10 dollars more for them to fly to London and home from Paris. Now July is peak travel which means that discounts are not as frequent, if any.

Kelley,
When I think of 'open jaw' travel, I only think of the first destination arrived at and the last one departed from. The travel in between is a whole different set of bookings that could be by train, plane or automobile, but they're not part of the original booking.
So for your trip, I'd look at it as:
Wash DC - Dublin
Madrid - Wash DC
That would be open jaw. You're going into and out of different airports. But what you've listed above looks like a multiple-leg itinerary built around a round-trip from Wash DC to Dublin. Unless that last weekend in Dublin is necessary for some reason, it's a wasted part of the trip. Unless you mean it's a layover on your trip to Frankfurt and not one of your destinations.
For our Italy trip, we're flying to Rome and out of Verona. That allows us to work our way across the country without using up time and money to work our way back to the start to do a round-trip. The cost was almost negligible to do this.

I guess I am doing same thig wrong, I have yet to find open jaw as cheap as round trip. I do fly into one main city( in last case London) and then bought serparate cheapo airfares and stuff for intercontinental travel, . Eurostar, then one way from Paris to Germany then another carrier one way from Germany to London, very cheap.
But even flying open jaw from say Vancouver into London then out of Paris is not as cheap as London return.
I do tend to travel during peak seasons though.

My O-J ticket is essentially a round trip ticket (SEA-CDG) as the main trip, but with Rome and Verona attached to each leg. My plan all along was to take this trip as it's one of only two SEA-Europe direct flights (the other being BA to London). So that may factor into things for me. The difference in cost to fly back from Verona (or even Venice) was ~$20/pp compared with coming back out of Rome. The train trip to get back to Rome is several times that cost.
Although I've considered Vancouver, I really haven't looked closely enough to know which European countries they fly direct to in order to price check. It is tougher from wester N.America.
With Kelley being in DC, there are actually a lot of different airports to choose from and the flight times/costs should be cheaper in comparison to those of us way out left.

I think part of the savings this time was that my r/t ticket before fees and whatnot was $525. Thanks for the multi-city thing. I wasn't doing that, but still, but it still had us about $600 more a person. I don't look at the Dublin as wasted time, since basically I want to see everything and go everywhere -- therefore the "where" is just more excitement for me!

What I mean by 'wasted,' is that you'll have already stopped there on the way in. If your main purpose to go back is just for the air travel home, flying open jaw would allow you to go to another new place and fly out from there.
Looking at your itinerary, that $780/pp seems like a heck of a deal!

Prices are higher in July.

We flew open jaw into Amsterdam, back from Rome. It worked out to be about the same as Round trip to Amsterdam. I actually bought tickets for Frankfurt and home out of Rome, and left the plane in Amsterdam because it was cheaper.

Some of the websites don't lend themselves to open jaw others will let you play with the destinations. I put a lot of possibilities in before I settled on the day, the destination and the price.

Previous advice is correct: consider open jaw reservations separately. That means into one city and out of another.
Then reserve your other legs separately. Search for the discount airlines in each country, e.g. ryanair.com, germanwings.com, easyjet.com, thomsonfly.com, or opodo.com.uk. Don't try to reserve all you legs at the same time.