And the WiFi on my iMac still takes 3 or 4 attempts to get to work - yeah, Apple's really lighting it up with their priorities.
Explain? My MacBook Air connects to WiFi immediately. I did have problems with it connecting to my AirPort Extreme when I had it set up using the 2.4GHz network. Once I configured it to only use 5GHz, the problem went away. I think it has something to do with the vast increase in devices (home phones, neighbour networks, etc.) using the 2.4GHz frequency.
You might want to try to optimize your network setup and the problem may go away for you. Your iMac should be connecting instantly and be ready to use as soon as the computer wakes up (You are just waking from sleep, right? Not booting up every day?).