No. I haven't used SAP2000. Also I'm still fuzzy on whether Brockman in second link I listed above is referring to nonlayered or only layered shell elements; whether or not his mention of transverse shear thickness factor applies only to core; and the exact differences between his Method 2 and the first link I listed above. Brockman doesn't delineate details; and NASA link is sketchy to not delineate advantages/disadvantages of its stated method. My main question is whether Brockman's Method 2 recommendation can include "equivalent" nonlayered elements, as the NASA link seems to claim.
I haven't tried your second method (I used a laminate element, so far). What about making all three layers coincident, which automatically connects them, then applying z' offsets to face sheet layer elements, if possible? I assume you're referring to offset face sheets in your second method; otherwise it probably would be far from the correct answer. If the strain (not stress) distribution is really as nonlinear as Brockman claims, then any of these plate methods, including the laminate element, of course might be somewhat inaccurate. For more study on the subject, a few more references were listed in thread507-14199. Good luck.