It truly depends on my mood -- there are days when I want to watch the action develop and there are days when I want to explore andt to imagine (remember) what her body looks like.
I can see how this is a different type of issue for some though and believe it may deal with how comfortable both partners are with their own and their partners bodies. I know a couple of years ago when I wasn't in the best of shape I preferred to have the lights off or even would wear a t-shirt

... If that's not motivation to get back to the gym.