But your method is free - built in - and preserves Apertures lossless workflow. For small objects I use it frequently, and it is preferable to using a plug-in. For larger objects inpainting will help, but if the background is cluttered, you may still have to retouch the resulting image afterwards in Aperture. Inpaint picks the txture to use based on statistics - not based on a semantic analysis of the image.
For a really complicated scene you will have to fall back on Frank Caggiano's initial suggestion - use a full graphics compositing program like Gimp or Photoshop.
Too complicated: let Frodo vanish:
Original:

Fixed:

Why is it to complicated? Because Inpaint has no notion of "floor" and "wall" and "table". Here a manual fix would be much better. This method usually works best with outdoor scenes and without objects touching or occluding each other.
Léonie