In reply to your question kg6mvx:
"Is it possible that some expressions of sexuality are wholesome and loving between one couple, but not another?"
Indeed it is! :0) We have been counseled to live by the Spirit of the law and not the letter of the law. This is especially true when it comes to sexuality between a husband and wife. Husbands and wives are free to make decisions sexually as a couple. We learn about these types of decisions through the example of Adam and Eve. God gave them commandments, but he also gave them the ability to choose. The choices may have come with consequences, but it wasn't necessarily a bad choice. The important thing was that they did their best to follow the Spirit and make the choice together.
When I was a newlywed, my wife and I were the members who had been raised on the "thou shalt not" version of the law of chastity, but were never taught what was okay to do in marriage. Being newly married, we thought "well...now what?" What is okay sexually and what isn't?
My stake president at the time was in my ward. He was an elderly gentleman who had been a member his whole life. When it came to law of chastity issues, he had seen it all. He is now a mission president.
Anyhow, I expressed my concern about not knowing which resources were ok to teach us about sexuality and not knowing what is okay and not okay in marriage. He told me, " We cannot tell you what you can or cannot do sexually in your marriage. Learn it, try it out,. If you as a couple spiritually feel good about it - it's okay. If you don't feel spiritually good about it or if it drives you apart, don't do it anymore." We're still worthy because we practiced it in marriage. Unworthiness comes when we know it's wrong and continue to do it.
Do be aware that what doesn't work for one couple doesn't mean it won't work for another. I believe this is why we don't have a letter of the law on this issue. People are individuals. Each are unique physically, are at different levels of progression and have different needs. As an example to illustrate this, I hate eating liver. It's repulsive to me, but for others they may love it. I believe we can look at sex in marriage the same way. I believe we don't need to make sex in marriage an ethnocentric issue - believing that what is good for you is good for everybody as well, or that your way is always the best way.
The nice thing is, if a certain practice done in marriage feels wrong, it's between you and the lord. You don't have to confess to your bishop. Sexual transgression to be confessed to your bishop are those done outside of those with our spouse.
Having clear resources on how to have sex - from LDS resources - wouldn't hurt either. There's too much porn out there disguised as sex education material. I and other members are working on remedying that however. :0)