I have an Airport Extreme on one floor and another one on the second floor as an extender. For some reason my device keeps connecting to the first floor Extreme - I know this because I can see it in the Airport Utility. How can I change this?
What you could do, is give them the same name, but dial down the transmit power for each.
The current AirPort Utility (the 6.x version) doesn't support this, but the old 5.6.x version can still be downloaded here: http://coreyjmahler.com/2013/10/24/airport-utility-5-6-1-on-os-x-10-9-mavericks/