I have read several times that some rokkor users says that 45mm f/2 is pretty interesting lens for it's lenght/apperuture and bokeh, also I've seen some very pleasant samples via flickr etc.

Besides 50mm f/3.5, good option might be 58mm 1.4 lens, if focusing isn't close enough to replace the macro, then it's better than 45mm f/2 for DOF shots and portraits. I'm using mine and loving mine very much.