With T1 I take my shoes off and sit cross-legged on the sofa. Which side of the sofa I sit on depends on my mood. I find that position helps me to be open, relaxed and explore my inner needs more effectively.
I have only seen T2 a couple of times but I sit on the right side of the couch (I think most clients sit on the left because he put the water there and last session commented that he forgot I sat on the other side.) I don't take my shoes off and I sit in a more adult and guarded way, which reflects the way I feel about him at the moment.
I only sat on the floor once when I was explaining some art to T1 and I knelt next to his chair. I enjoyed being physically closer to him.