Gatorskins are, um...okay.
They came with my very first road bike (was a MTB'er for many years before that) and I kept running them since I didn't know any better. I will give them this, they are tough, long lasting and flat resistant. I am confident that I would probably never have a sidewall blowout on a Gatorskin that was in good condition, which is one reason I am thinking they would be good on the tandem, for starters at least until I gain more confidence.
I was converted to the Jan Heine way of thinking about tires when I was riding brevets a few years back, that being, run a light thin tire with optimal deflection for your size. It's basically conserving effort, and if you get a flat, then that's just more rest.
That being said I have had sidewall blowouts with the Michelins and bulges with the Grand Bois that rubbed the brakes so much I eventually had to stop and put on a spare. I'd rather avoid with another person on the back and the higher speeds obtained on downhills with the tandem.
So I guess my goal is: tough enough so that I won't suffer any undesirable tire conditions, but light enough so I won't bemoan my heavy tires all day
Easy enough, eh?