My Mom has done Grand Circle and
OAT.
She's 70, fairly active and usually travels with a group of other women, but I suspect she'd be happy going solo on their trips, too.
FWIW, she told me that she was talking to someone recently who was in Egypt on a Grand Circle tour when the riots and protests broke out. Grand Circle apparently chartered a plane and evacuated them very quickly. The person my Mom spoke to was very impressed with Grand Circle's quick response.