mmm, you could really get a good grip on those butts... err I mean buttresses 
 
For photos fairly close to the buttresses I'd suggest changing your viewpoint slightly so that you have a buttress starting within the frame, rather than coming on from the side when its already quite large. This would lead the eye into the trunk, rather than having the buttress appearing as a wall coming in from the side.
A wide angle lens is generally necessary to have good focus right along the buttress, and viewpoints from near ground level can look great.