I know I am not the norm but all my children still see my husband and I naked and no one has expressed any request for us to cover up. If they did I would absolutely respect that and do so. I LOVE to strip off and skinny dip after a hot day (my two littest kids do as well).
My 17 year old still sees me in passing. I am never overty "in your face" naked in front of him or in any sexual way (I don't kiss my husband naked in the pool in front of the children etc.) but he will carry on conversations with me while I am naked in the pool. He never diverts his eyes or worse yet focuses to long on any one body part. If he started doing that I would cover up more often.
We sleep naked and the children mostly sleep in just boxer shorts so goodnight hugs are usually "skin to skin".
I think it depends on your comfort level as a family. My 10 and 17 year old are VERY modest and I have not seen them naked in many years, yet my husband and I as well as our youngest two are very "naked people".
I don't think nudity neccesarily equals sexuality. I don't like my daughter to play with nude Barbies because I don't want her experimenting with putting them in sexual positions etc. But I don't mind if she sees the actual human part on her father or nudest brother. It is not in a sexual context and it teaches her not to be bashful about it.
My boys are somewhat "ruined" on breasts anyway...for instance I was once at a movie with my oldest son (he was about 11 at the time) and a nursing mom sat next to him. She leaned over and said "I might need to nurse my baby during the movie would that be okay in front of your son?". My son replied (loud enough for the whole theater to hear) "Oh that's okay...my mom and her friends all nurse their babies they are always whipping their boobs out in front of me!" That's what I get for having the lactation support group meet at my home, but the theater got a good chuckle out of it.
My advice would be to follow your comfort level and try to read his. The "skin to skin" contact that felt so good as a baby still feels great when they are a rough and tumble 7 year old.