I understand that you want to avoid spending unwanted sectors, benoit - we all do - but I don't understand why it's a problem doing that. That's pretty much the default, unless you log into some engine and click "cheapest fare up to N stops". You wouldn't do that for a OWE.

I normally plan from the CX downloadable trip planner, and if I want to fly LHR-SEZ, I tell it that and it lists all the flights it thinks makes sense, I believe starting with the non-stops, then the direct flights.

If you see a direct flight in the list (it shows > 0 stops) and you want to see where it stops out of curiousity, you can click on the details tab.

OTOH, if you happen to *want* to see Nairobi, you just ask the planner for LHR-NBO.

For cases where you have to make a connection (no direct flights) and it has shown you cnx through a city you're not fond of, you have an option to have it try a different city, e.g. LAX-JFK via ORD or via DFW.

It seems to me that the only real problem if learning which OW carrier actually serves NBO (bad example these days), and from where.