My input is to buy a lens for a needed purpose. You seem to have focal lenghts well covered, the 135mmL is wonderful, but doesn't fit what you say you do.
I'd consider a upgrade to your body if you have no specific lens need, and the money needs to be spent. A 5D MK II is a bargain right now at about $2,000, and fits your budget. Otherwise, just sit tight and wait to see what other cameras and lenses are introduced this year. The 24-70mm MK II looks like a huge improvement over the old lens, but wait and see.