There's no luck involved. At any given time, each city has a specific preset destination it will ask you to go to, and one of those is always Jeuno. There's a tracker you can use to see which destination is tied to which city at any given time:
http://www.mithrapride.org/vana_time...racetable.html
I thought you could just decline in one city and try the next, is that really not an option? Does declining a long run actually lock you out for the... looks like 57 minutes and 36 seconds each set of pairings is valid for?