I really like the HQ flights for a GCC. Mine was not hard on her cage at all, so it wasn't an issue as to bar thickness. It gives them a ton of room, is inexpensive and it isn't the ugliest flight I've ever seen.
As for GCC's being on a playstand, you really need to worry about independent play with them. They NEED to learn to be out of the cage and playing on their own because if you let them, they'll spend all day and night snuggled in the crook of your neck. Which is nice, except when for whatever reason they can't be there. It causes more behavior issues later than it's worth. Independent play is essential in any bird, but especially one that is so much a cuddler. They just won't understand why they can't cuddle all of a sudden.
My GCC loved her stand. She spent most of her time with me, but did learn how to entertain herself by being left on her stand regularly.
