How about Tumblr? It's respectable enough that mainstream corporations have Tumblrs, while still being very permissive about sex and nudity. Dunno how long that can last, but so far it has. A lot of artists post there.
If you do post your art at Tumblr, and want to participate in the social aspects, make sure to use your main account. Tumblr lets you created as many blogs as you want, but only the main one lets you communicate with other users. Dunno why they do that, but they do.
I've had two dA accounts...the current one for about 2 yrs. The first...many years ago, but switched email accounts and lost the password to it...and no, I couldn't get it recovered, but that's beside the point. In the many years I've been there, mostly lurking in the background, I've seen a definite change in the site...it used to be 'ART' and doing things that may be outside the mainstream/push the boundaries but usually was not what could be considered 'pornographic'...yeah, lots of nude/nakedness, but rarely things that would garner an NR-17 if it were a movie.
Now, it's become a teeny-bubblegum hell...with the 'pervie' adults lurking in the background...almost two separate communities on the same site, each vying for dominance. A lot of the 'fun' is gone and with it a chunk of the character...
I used to not pay much attention to DA in the past but i was told many times i should have my images posted for others to see more than just at rendo, so i set up an account. I like it, easy to post, easy to categorize and easy to link to images there. I don't like the social aspects of it so much, to much work LOL. Of the few times i have had the time to cruise through the other images posted there, i was amazed at some of the talent and quality. So far i have had a great experience posting at DA and i like the name, then again i am not prudish, even turned some of my co workers and employees onto the site.