Re: What do you do to protect your instruments from harsher environments?
First thing is to get a digital hygrometer, a device which measures relative humidity. Planet Waves and a couple of other companies market them. You can also get them from a cigar store. I like the ones that have adjustable calibration, and you can find tips on the internet to test their accuracy. Most are small enough to fit in a guitar case. You want to shoot for a RH of 45--55%. One of the things is stability, so your best bet is to keep your guitars in their cases so they slow down the rate of change. Your guitars are always safest in their cases--from changes in temperature, humidity, (and the occasional 6.5 quake!)
So in dry weather (LOW RH), you need to moisturize. And just like your skin gets dried out and uncomfortable, so will your guitar. One rule of thumb with guitars is: if you're uncomfortable due to temperature an humidity--so is your guitar. And they don't like fast, overnight changes. There are several guitar humidifiers on the market; again by Planet Waves, et.al. Most of these are directed at acoustic guitars which can crack because of the thin woods. Most of the time with an electric, the first symptom will be fret sprout--but that can lead to more major issues. These humidifiers will fit in the case, and many are designed to fit right in the round sound-hole of an acoustic. But it is simple to make your own.
Some folks like to use 35mm film rolls, others like a small plastic travel soap box. Punch some small holes in the case. Then, simply cut a piece of sponge to fit, and dampen it with DISTILLED water. Remove any excess water--you don't want it leaking and making a mess in your case. Put your home-built humidifier in your case with your hygrometer, and re-dampen as often as necessary to hit that 45-55% RH mark.
In my cleaning maintenance, I will often use a damp rag directly to the fingerboard, and then in a few seconds buff it dry. This will remove about 99% of the DNA and grime that coats them, and help restore needed moisture. I try to wipe down my entire guitar after each playing session to remove the sweat and grime.
With only one hygrometer and several guitars (and a humidifier box in each case), you'll need to move the hygrometer around. I usually let it stay in each case 2-3 days to get the most stable reading.
Now, you can basically do the same thing on a grander scale with the wet towel in a box trick, but they do sell room humidifiers at places like Sears. They're not that expensive if you want to go that route, and they are well worth it. I'd probably keep doing the case humidifiers too, while it is so dry. You can even buy whole house humidifiers if you need too.
Taylor's web-site had some great little "White Papers" on how to properly humidify your guitars. I strongly recommend you read these, and familiarize yourself with the symptoms of a guitar that is either too wet or too dry. I think they still have them, so be sure to check these out.
And finally, some of you may live in a summer clime where you have plenty of humidity. But when fall starts, the heaters and the wood stoves start getting fired up and BAM! You've got a dried out guitar. Again, get a hygrometer and make or buy some case humidifiers and keep them in your cases. Your guitars are safest in their cases, and the case helps slow any rapid changes in temperature and humidity. I can't stress this enough.
I hope this helps. Good luck!
Bill