I'm a straight male, so I'm going to be unable to address your question directly, but perhaps it isn't the positions that are causing the lulls, but rather the locations. The same positions can take on completely new connotations if they are done in different areas. Maybe you could consider different rooms, outdoor vs. indoor, semi-public vs. private, etc. Even being spontaneous vs. something tried and true can get you out of that rut and get you wanting to be more adventurous.

Hope that helped some.