I always like reading tech stuff in the magazines, and the March issue of Premier Guitar has an article on humidity and guitars.
One product they mentioned in it is called Hydrate from Planet Waves.
I ended up ordering some from Amazon earlier in the week.

Be sure to read the upper right side of Premier's article on wood conditioning, because if you have a maple fretboard, lemon oil is better for it than the Hydrate stuff.
The latter will turn your fretboard reddish pink.

I also bought a bottle last year of Fret Doctor, as I hear that is good stuff too.

And today in my email I received an email from Stewart MacDonald on fret erasures.

And several months back I got some Gorgomyte from my local PRS dealer.
This stuff is suppose to be very good too, and here is a video on using it.

I may end up ordering the erasers from StewMac later.

So have I used any of this stuff yet?

All of my guitars I only get a chance to play them on weekends, and the strings are still pretty much like new and sound great.
I run Ernie Ball Cobalts in 9 - 42 on all of them, and the Cobalts seems to last a long time.

First guitar I end up changing out the strings on though I will give it the Gorgomyte treatment first, then spray on some of Planet Waves Hydrate.

Please feel free to add comments on what you use on your guitars, and if you have used any of the above products and if you like them and have had good success with them.