It's so hard because there are so many wonderful kitties that need a home.
I think you are doing the right thing by getting Gracie a friend. She is young and now is a good time to do it. I'm thrilled that you are going to adopt from a shelter!!! That's a wonderful thing to do.
My suggestion to you is to go to the shelter when your ready and I promise you will know which one is the right one for you. Let the kitty pick you and it will be right. It will probably be none of the ones you think you want but you will know it in your heart.
Keep us posted!!