Doubletree's don't really need many mods. Unbelievable, they were pretty well planned out by the time we got our 2006. I did sew up some simple lined curtains & do notice it's helped us block out the high temps outside. 82 deg at 5am, so another triple digits today. Last summer we needed the foil covered bubblewrap to insulate the windows. It still felt like a hot cave. Yuk.
But I do have some ideas to change out the furniture. Just can't talk DH into spending any money right now....