Best bet is wired GigE to the router or a fast POE adapter or an expensive 802.11ac access point (goes to the GigE on the Mac)/QUOTE]
I assume you mean Ethernet over Powerlines, not Power over Ethernet, which is quite different.
For the original poster: I'm not sure what their real-world, practical throughput is, but some newer Powerline models claim 500 Mpbs (rivaling theoretical 802.11n speed, but the real question here is how they actually perform in your situation). Some older ones claim 200 Mpbs. Many people get by on a wired 100 Mpbs home network, so if the Powerline adapters come even close to that, you might be better off with this if wireless is bad for you. However, it sounds like 802.11n (theoretically faster than the previously mentioned Fast Ethernet but not rivaling Gigabit) is working at least decently well for you right now.
My wireless works pretty well, but lately I've been noticing some issue stemming from outside conditions. Not a big deal, except that I consume my media through the Apple TV with my iMac acting as the source for all of my media. I tend to strive for really high quality rips, so I'm looking to circumvent as many of these issues as possible.
It sounds like figuring out a way to run a gigabit line from my basement, to the outside, and back in to the addition is really the only (long-term) suitable way of accomplishing this.