Anything is permitted in the bedroom provided it is by mutual consent, does not violate scripture, and is between a husband and wife.  Therefore, fornication, bestiality, adultery, pornography, voyeurism, sodomy, etc., are not permissible.  Oral Sex is permissible as is fondling, caressing, and mutual stimulation.  Of course, all of this is intended for the married couple:  husband and wife.

What about different sexual positions?  Again, as long as it is by mutual consent, does not violate scripture, and is between a husband and wife, then go for it and have fun.