or how about more than two cities.. i also organise events would be happy to invite people form other cities close to zurich :-) ie bern, basle lausanne etc etc..

The danger then is that when people post an event they will choose the option which gives the greatest exposure, ie. All cities.

If that happened I for one would quickly get annoyed constantly seeing events that are irrelevent to me as they are in cities hundreds of km. from where I am.

I understand your POV.. i feel the same i wouldnt want to see events not relevant to me. However i do have people who come from Geneve, and Luasanne to my events. I also know of a few people who travel to Geneve for events from Zurich.

The alternative to this is to duplicate the event, when you post it, but then with the alternative city posted.