I've spent 4 hours reading the forum and I am still not clear about how to book a stopover. My understanding is that it is usually allowed on international flights, but don’t see how to add it without a huge jump in fare price. Let’s say I want to fly to Moscow from IAH and on the way back stopover for 4 days in FRA (common connection city). A normal round-trip IAH- MOW is around $700 on ITA, but when I go under the multi-segment trip and start adding an additional segment in FRA, the price jumps to $1600. Any suggestions? How can one search only for fares that allow stopovers? Thanks a lot.

Try expertflyer.com for more fare rules. Good luck!

The cheapest fares often don't allow stopovers. Perhaps you are confusing a real stopover (over 24 hours) with an overnight stop (less than 24 hours). Stops of less than 24 hours are generally allowed on the cheapest fares, at no charge. But generally you will have have to move up a few notches in the fare class to get "free" stopovers.

For cheapest way to get a few days in FRA on the way back is probably to book an open-jaw MOW-IAH + IAH-FRA and then a cheap one-way FRA-DME on Air Berlin or some other low-cost carrier.

Most of the lower-tier fares on most carriers will have "no stopover" rules, though you could still stay up to 23:59 between flights without it counting as a stopover (vs just 4 hours domestically).

I tend to really max out stopover and open-jaw rules on AWARD tickets, where things tend to be more flexible. Once did a 25K award out on MNL on CO that went MNL-GUM (daylong non-stop stop)-MAJ (final destination, stop)-YAP (stopover)-GUM-MNL. Why see just 1 place when you can see 2 or 3?

Also once did ATL-ROR (stop)-MNL (stop, open jaw), BKK-ATL even though the agent swore ROR wasn't an allowed stop. The online booking took it.

I guess the legacy airlines figure that if people did stopovers on paid tickets, anarchy would result. They're only slowly getting comfortable with the idea of one-way travel. Change takes time.