I wonder if this is [To Open the Sky by Robert Silverberg][1].

I was going to post the cover in case that jogged your memory, but the book appears ti have been published with multiple different covers. You can see various of the covers used on [the ISFDB entry for the book][2].

It has tanks similar to the ones you describe. The book calls them Nothing Chambers and says about them:

>Half an hour in a Nothing Chamber restored a man to vitality, draining the poisons of fatigue from his body and mind. Three hours in it left him limp, flaccid-willed. A twenty-four-hour stint could make any man a puppet.<br/><br/>
Kirby lay in a warm nutrient bath, ears plugged, eyes capped, feed-lines bringing air to his lungs. There was nothing like crawling back into the womb for a while when the world was too much with you.

The cosmetic surgery you remember is a closer match and in particular the plastic ears. The book includes this scene:

>Kirby bit his lip in anguish. A girl in the pew just in front of theirs turned around and said in a low, urgent voice, “Please. Please—just listen.”<br/><br/>
She was such a numbing sight that even Weiner was struck dumb for once. The Martian gasped in shock. Kirby, who had seen surgically altered women before, scarcely reacted at all. Iridescent cups covered the openings where her ears had been. An opal was mounted in the bone of her forehead. Her eyelids were of gleaming foil. The surgeons had done things to her nostrils, to her lips. Perhaps she had been in some terrible accident. More likely she had had herself maimed for cosmetic purposes.

The book was published in 1967 so it matched your time frame (the Google Books article I've linked gives the date as 1999 but I think this must be the date of a rerelease).


  [1]: https://books.google.co.uk/books/about/To_Open_the_Sky.html?id=Ge5PPwAACAAJ
  [2]: https://www.isfdb.org/cgi-bin/titlecovers.cgi?38270