Shaggy, they/you/your neighbors, the whole county will love it. If flank or sirloin, medium cuts are great but I've been getting into the thin cuts for everything. Just seems to light a craze. Everything cooked between rare and med rare, all depends on your family. Enjoy!
P.S. Need to clarify, When I say medium to thin cuts I mean when you slice it across grain for eating. Thickness of the cut before grill can be whatever you desire. Just be careful with skirt and do your research, it's can go tough real quick.