Positioning is key

In sex as in real estate is it truly all about location location location? The wife and I have pondered this a lot. We bought the Kama Sutra and several other position books. It was obvious that body type and flexibility play a large part in attaining a successful position. However other problem arise such as couples height ratio, height as well as density of sexual medium (i.e. bed couch etc.). I believe that beds should come with a sexual difficulty rating. You can get stuck in the frame of water bed or get lost in memory foam before you even realize it. Such things can throw off your rhythm or throw you off completely. Has anyone else found any difficulty when enacting a particular sex position? Ten years and several partners and the 'wheel barrow' still eludes me.