Personally, I use some exterior grade double sided carpet tape (Duck brand i think?) that I get from Menards. It's 2" wide. The key is that your platen backer needs to be close to perfectly flat and very clean, and you need a little safety ledge at the bottom. In the years (and multiple pyroceram platen replacements) that I've used it, I've never had it fail, and that includes times when the platen backer was too hot to comfortably hold my hand on for more than a couple seconds.
When it comes time to change the glass, just heat the platen with a heat gun or torch, pry the glass off with a putty knife, and clean with acetone (or whatever) to remove the residue.
I've seen a few guys use VHB tape from 3M, which I've used for other things before. It's a very good tape, but costs a bit more than the carpet tape I use. One roll of the Duck brand tape should last you the rest of your platen changing life.
One guy I knows recommends storing tape (or really any kind of adhesive backed paper, stickers, etc...) in a refrigerator. Supposedly makes it last longer?
