I always remove the brake reservoir cap. By doing so, the brake fluid will settled torwards the caliper. I dont normally crack open the bleeder valve but its definitely a viable method. Ive just had a situation in the past where the bleeder valve broke off... and I needed to buy a new caliper even though the caliper was fine. Could not successfully remove the remaining bleeder valve fragments.

 

I always open the bleeder when compressing the caliper on anything I've ever done brakes on.

 

Yip, those are the two options up for debate.
If removing the brake reservoir cap is what is actually in the GM manual, which would be nice to know for sure, then I think that would be the easiest.
Though still hear of people mentioning possible issues in doing it that way, but yet to see anyone post that they actually hit said possible issues with our cars doing it that way, so...
Just would be nice to have confirmation as to what's actually in the GM manual.

 

I always take off the cap