I also like the songs he made after Cilla left him (
http://www.youtube.com/watch?v=u9sRJ-eOHnc)
He really connected into the pain of humanity there, so most people could relate to as opposed to just bein a Rock-Star in an Ivory Tover.
Anyway, "Commercial" in itself doesn't have to mean worthless. There are many reasons why an artists might end up as very commecial, a lot of it which can be out of his control, as there are so many working full-time to manage his carreer and take it in the direction the record company wants. So I think that part of it is pretty irrelevant - he was the great rock'n'roll singer of his time and his image and performances had to live up to that.
To appreciate it I think you need to view it in a different way. First appreciate him for what he was as a person and a performer. Then there are some real gems there, but they can be hard to find among all the rubbish we was made to do. He was worth an insane amount of money, so I can 't imagine him having too much freedom when it came to his song choice, etc. I understand this was very disillusioning for him, cause although he wasn't a writer, words means everything to him, phrasing meant everything to him, and he hated to compromise quality or be untrue to his own personal style.
Anyway, the more I've seen of Elvis the more impressed I've become. He was a very moral and God-fearing person and had a really strong soul that came through to people (the ability to generate that level of worship is a spiritual skill). And he did all this naturally, in a way, it was just who he was and he was just expressing himself from his heart. There was no conscious agenda to get control over people, or take over the world, and I just respect him more for that.
I think his ambitions were more spiritual and this was also his strong point.