Are all of your devices AC capable yet? If your house is anything like mine it takes a while to get the bulk of them moved over. That said, if you are the tinkering type, buying a wireless router that supports DD-WRT is a good idea. I was able to convert my L3-only wireless router into an AP using the software.
Rathji is on the money with his assessment, you will find in all likelihood that the clients are going to try to stick with their first connection, even if the signal strength is marginally better on the other AP. The decision is client based and you will have to modify each client (if possible) if you want it to jump between networks more frequently.
Read:
http://www.intel.com/support/wireles.../CS-030101.htm