i use eyeglass spray and a microfiber cloth
Right on! If you have to use liquid, this is the stuff you want to use as it has additives in it to prevent scratching or chemically altering the screen. I use this microfiber cloth as well:

I give these things to people for Christmas and they are like "WTF you gave me cleaning supplies?!?!"...after they use it they are like "OMG this is AMAZING!"