I think he was happy in his to a point. During the later years of his life even though he tried to show us that he was having a good time but in truth he wasn't. He was in much pain. He hated Vegas because he was performing at the same place year after year and pretty much mostly to the same crowd. Same to Lake Tahoe, year after year. He was getting tired of that. He tried his best to have a good time by putting on weird hats, glasses and so on. But I think he really wasn't having a good time. It was the drugs that he was taking that was making him have all that pain. But through it all, I think he was happy about what he was doing.
I believe if he would of got rid of Colonel Tom Parker he would be better off. He can do what he wanted to do. I think we all know that Barbra Streisand tried to get Elvis to star in A Star Is Born. He only he didn't have Parker at that time and Elvis would did that movie. He would of got in shape for that movie and maybe he would of still be alive.