If you are looking for a challenge, Hoya wallichii may be for you.  I rate it as an 8 on a 10 scale of difficulty with 1 being dead easy.  This is my experience with it; it may not be yours.  It has a wonderful, large, albeit very short-lived, flower with virtually no scent.  It is a plant that is probably best left to very experienced growers with the ability to give it what it really needs.  If and when I can get a photo of its flower fully reflexed, I will bring it back.