........ You just have to get closer than normal to your subject to narrow your depth of field. This may make your human subject uncomfortable and act less natural.
Yes, thats one of the reasons I got the 180mm 3.5L macro. Gives more more distance from the subject and the amount of bokeh is more than the other lenses due to it's longer reach. See a comparison of Bokeh of the Canon 65mm/100mm & 180mm here: http://www.the-digital-picture.com/Reviews/Canon-EF-100mm-f-2.8-USM-Macro-Lens-Review.aspx Go down about 50% of the page to see a comparison.
Ofcourse, this might get too long for you then, but will do very nice portraits and Macro all in one.