I was lucky enough to see Dolly Parton in concert in Cardiff earlier this year. She mentioned "I Will Always Love You" and said that she wrote it with Elvis in mind, but when Col Parker wanted the rights she withdrew the offer and had a hit with it herself. She also stated that she was sure that Elvis had no idea she had offered the song for him.
I'm sure he would have made a beautiful job of it, such a shame it never happened.
Dolly's concert was awesome and she mentioned Elvis several times, and appeared to be a real fan of his. Imagine if they had met, what a photo that would be!