Yes, relaxing and arousing describes it. My lady and I often trade backrubs, and we enjoy both giving and receiving. Once you get used to it, it's only a small part of the pleasure, but there is a thrill in knowing that the one who's astride has his/her legs wide apart and bare crotch pressed down against your skin. But really, you can't tell what body part is in contact there, and having gentle hands running up and down your back and around your neck is so good...there's so much to enjoy!
4 days after I met my current boyfriend I gave him a back massage, sort of to initiate things. He works at a really hard labor job, and told me he had never had a back rub before when I suggested it. He lied down on the bed and i rubbed his back for hours while we talked, I didnt even notice the time passing so quickly. In the end he admitted the reason he didn't ask me to stop was that he didn't want to turn over knowing he had such a hardon and a precum spot on his pants :O . It turned me on a lot as well.