Favorite couple?
While I loved the married/over-the-excitement-morning-sex couple (also loved that they were played by actual husband and wife) and I loved the trying-so-hard-to-get-pregnant/fertility treatments couple, I would have to say my favorite was the older woman with a younger man couple.
I found the whole sex tape thing hilarious, as well as how easy it was for her to convince him to make one with little effort and without him realizing the entire thing was orchestrated. They had great chemistry and a great exchange of dialogue.