One other method you could try is your normal #1 method. Once you have as close to straight of grain as possible with that method, then pull threads off the cut end until you get a single, long strand the WOF. It's not quite as tedious as trying to pull the thread out of these very tightly woven cottons but can still be a messy pain. But you will get a true straight of grain then - if it's really critical to you. Then, as you say, when printing of the design is not...you have to decide with factor is more important for you.