I have had scheduling problems many times with itineraries I booked through Expedia, and the airlines involved always rescheduled me, given me hotel and meal vouchers when necessary, and put me on the next available flight, often that of a different company.

In fact the worst problem I've ever had was when I bought a ticket from Lufthansa with a connection in Mexico City, and a connecting flight on a Mexican regional airline. On the way back, we missed the connection because of congestion at the airport, with a long wait for the gate. Lufthansa gave us no help at all, other than to put us on a flight the next day. We had to find a hotel, and pay for it, on our own. This had been sold as a single itinerary directly by Lufthansa, and there was no indication on the ticket that the regional airline wasn't a Lufthansa partner.

Maybe the problem with the Iberia flight was that your friends weren't willing to take a later flight.

Expedia doesn't overbook flights. They only sell tickets the airline makes available. Also, people who book through reservation sites have all the same booking rights, by law, in the US and Europe, as passengers who bought from the airline. But those rights don't include getting upgraded to Business class, although airlines have been known to offer that. What they usually offer instead is a rebooking on a later flight, and maybe a free future ticket.

I should have added that if you get bumped, you're entitled to monetary compensation if you don't accept what the airline offers. If you voluntarily upgrade yourself to Business, technically you haven't been bumped.

The regulations for what happens in the event of a missed/canceled/whatever flight are different in Europe and the US.

My takeaway from bvlenci and thursdaysd's excellent posts is that it pays to be informed about your rights as an air traveler, regardless of how you got your tickets.

Informed, yes, and from what I've heard, skilled at having one's rights upheld. Not always a given.

Informed and assertive, agreed!

I would just poke around online. Start with something like Expedia to get an idea which carriers go between your home city airport and where you want to end up. Then go look at those airline's own websites.

There's nothing wrong with using a Travel Agent if you feel insecure doing this yourself. But I don't really see any benefit to it.

Expedia is NOT the best place to research airline routes. The airport websites are the best places to find which airlines serve them. Othersie, besides itasoftware I find skyscanner pretty comprehensive.

Confused? Me too. So much information, and I have booked many trans-Atlantic flights. So: A few hints -
www.itasoftware.com certainly is a good source of information. To translate to a ticket, or a combined ticket, you may have to telephone the airline. This old-fashioned technology still works, however inconvenient.
Multi-city tickets have advantages but you must use the multi-city or multi-destination search function.
I agree that booking directly with an airline is a good idea, especially to get advance seat assignments. But some itineraries require combining airlines which do not sell each other's tickets. Then it makes sense to use an on-line agency which puts the tickets together for you. Just be sure that the itinerary you choose leaves a substantial amount of time for any change of planes. Better to twiddle your thumbs (or scrutinize a duty-free shop) for a couple of hours than race through an airport maze such as Charles de Gaulle only to find the connecting flight has closed its doors a half-hour early.
My faves, beyond itasoftware: www.cheapoair.com; www.hipmunk.com ; www.travelocity.com ; www.expedia.com ; www.skyscanner.com for European one-way budget airlines.
The bad news is that no agency can offer very much help when things go wrong.

OK, thursdaysd, you lost me. Expedia makes it easy to search routes, fares and carriers. Your categorical objection makes no sense to me.

It's my impression, and you're welcome to prove me wrong, that Expedia doesn't list all airlines, or all fares for the airlines it does list. Plus I prefer to do my searches on sites that don't themselves sell tickets. Have you tried sites like itasoftware and skyscanner and found them more difficult to use?

It's always worth trying......

When we went to the US from Paris in November, we had lots of alterations to our itinerary on Air France/Delta codeshare. The final straw was CHANGING THE DAY of our return flight, which we refused to accept and were finally given a flight on the correct day, but from JFK instead of Newark - which involved a long drive for our hosts.
Anyway, a short time after our return, we got a letter of apology from Air France and vouchers of €150 each for a future flight.

itasoftware is great if you are booking convoluted routings, fare codes matter to you, and you know how to use the search commands. Otherwise, kayak and hipmunk will get you what you want.