I think at first Lisa had very little say in it Priscilla opened up Graceland if memory serves me right. I think for Lisa now it Graceland is a place where she can let others see how great her Dad was and for people to focus on the positive aspects of Elvis.
She has a lot of stuff away from the public. The very personal items she has keep private. In the Oprah interview she took her to an area the public doesn't see where his clothes, etc are kept.
I think Graceland serves not only as a place where people can pay theirrespects to Elvis but can feel connected to him as well. I think that would be hard to do elsewhere.