I'm not for Guam, nor for a heavy wind speed area, but this is the question that is too general to obtain a direct answer.
What is the span, the loads, the roof pitch?
All of this will define the Section Size, which depends also from the spacing. You can create some spreadsheet, or find one, and test, for your particular case, which combination of spacing and section size is more economical. The limit spacing will depend on the maximum distance that the roof can Span.
If your question is more related to availability of secrion sizes, then contact the local companies.
I'd have to look it up, but I imagine Guam is subject to hurricane-force winds. The fastening of the roofing and siding will be critical, along with uplift of the roof structure. There is a lot to think about and engineer (projectile-resistant glazing comes to mind). Consult a structural engineer. There are no simple answers to such complicated questions.
