A little confused. I gifted my wife a Cat 1-7 award and a Guest of Honor reservation.
When I went to her account to redeem, I selected Guest of Honor and then picked the room type, which said it would cost 1 Night. The option to pick it, though, was greyed out and says "To combine this award with the other award applied, please contact 1-800-544-9288 or your Global Care Center."
This seems to imply that it's possible to combine a Cat 1-7 award and a Guest of Honor award, but when I called in, I was told in no uncertain terms that it's not possible.