My rule is that Wi-Fi is only for items that are meant to be moved often (e.g. laptops, smartphones, etc.). HTPCs, PCs, and such are all run off Ethernet. Although, I still have to properly run my wires through the wall and then do all the speaker wire as well. Right now, I've got wires running through the hallways and such, which looks a bit garish, but it works.
I'm also switching to in-wall speakers and wall-mounting my TVs to go for a cleaner look. It'll be a slight degradation in sound compared to my existing floor-standing speakers, but it should be fine.
I've been adding about a billion project ideas to my "list", which gets worse whenever I notice how the original owner cheaped out on something. I'm always really timid when I feel like I'm invading someone's personal space, which made my home buying worse because the homeowner hadn't moved out yet. So, I wasn't nearly as willing to just dig into every nook and cranny. Oh, and if the person hasn't moved out yet, mandate cleaning in your contract. It was pretty disgusting when I went to use the shower after finally getting everything moved in, and I found hair and grime all around. D:
Also, if there's a pool, mandate that the chemical levels be set to
standard levels. Pool companies are lazy bastards and jack up the stabilizer to keep the chlorine from fading (caused by UV rays), but high amounts of chemicals are often much harder to manage. To give you an idea, stabilizer (cyanuric acid) is often kept between 30-60 ppm, and mine was at
300 ppm. Reducing that down to the current 40 ppm took five 1-foot drain and refills over the course of five days. It was
not fun and
not free. I'm currently fixing high Total Alkalinity, which requires you to drop the pH to 7.0-7.2 and aerate the pool while it raises back up to about 7.6. It still takes a while as it normally only drops around 10 ppm at a time, and I'd like to go from 130 ppm to about 80 ppm. (I'm currently at 120 ppm

)
Ultimately, I guess the best advice is
never expect the current homeowner to "do the right thing" (such as cleaning). If you want it done, put it in writing.