Hoya leucorhoda is a little known PNG native that comes with a very high recommendation from me.  It flowers much more readily than many Hoyas and has a large beautiful bloom.  Some of the leaves are heart-shaped, thin and it is a very vigorous grower.  Like most Hoyas it will do better with supplemental light in the winter time in the north.  It can also be quite susceptible to spider mites – so keep a look out.