When troubleshooting Wi-Fi connectivity issues, I find the following resource has the most relevant information:
Furthermore, you may want to avoid giving your network a common name. While the following article (and excerpt) refer to iOS devices, the same applies for your Mac:
If you were to give your wireless network a common name (SSID), users of your network who use iOS devices [sic] and are away from your network would run the risk of joining a different network with the same name. Having joined the unexpected network, they would be exposed to potential data theft.
Because of this security issue, Apple maintains a list of common or ambiguous SSIDs, including the default SSID for many commercially available access points, as well as the SSIDs "wireless" and "default". If your network's name is on the list, any iOS device [sic] that joins the network stores the access point's BSSID and associates it with the network's SSID. Subsequently, it will only auto-join the network if the access point's BSSID matches the information the device has stored. This avoids joining a different network with the same name.
Therefore, you may want to refer to the following article when configuring your Wi-Fi router:
Had the same issue and finally solved it. After the upgrade to Mavericks our 2 new Macbook Airs stopped connecting automatically to Wifi while the older machines the kids had still worked fine.
Bought a new airport extreme and problem solved. Our Airport Extreme was about 5 years old and was probably not compatible with the new OSX.
BTW this was after trying everything people suggested on this forum and a 4 hour marathon tech support call with Apple where we reinstalled the OSX.
***** to need to spend $200 but glad the problem got solved.
New extreme is also mega fast so its all good.