So, what I'm hearing from various sources is that for higher pressure applications two layers of tape is recommended? Or do you feel that it should be used on both higher and low pressure applications?
I've got the Stan's valves, tape, and sealant on the way.
Stan's tape double wrapped will hold any pressure you would realistically use. Almost any rim tape double wrapped will hold any riding pressure. The one exception would be Scotch 8898 and 8896. They are thinner and I would double wrap for low pressure and triple wrap for high pressure (beyond ~60 psi) applications. They are a fraction of the cost of Stans and are easy to use. The only other thing I can think of is to look for burrs around spoke holes on aluminum rims before wrapping your tape. Sometimes the spokes holes aren't finished perfectly and a burr will pierce rim tape really easily.