My niece cooks all beef well done. Hard to chew and sort of sad. Great idea about the rib eyes. Never thought of that.
A word of caution: use the indirect method for rib eyes. If you grill them directly over the heat source the fat drips, causing flareups which can deposit soot on the meat.
Convince her to braise the beef -- crock pot, dutch oven, etc. Even the toughest (cheaper) cuts come out tender, and the tougher cuts have more flavor than the expensive cuts!
My MIL made pot roast in a pressure cooker which was amazing.