There is always the old trick of 'lets write down our fantasies and share them'. Suggest this to him, you both write a list and then you swap and discuss the lists. Make sure you tell him that there is no judgement or criticism allowed and that you both promise to try out at least one thing from each other's list sometime soon.

This takes away a lot of confrontation and potential for argument, can be a fun activity to do together and may reveal somethings about your husband that you did not know...