Having used the 70-300L and the 16-35f4L I can say without reservation that they are the perfect travel combo. But there is one thing missing, a decent, fast 50mm for the middle range and low light. Both Sigma 1.4s and the canon 1.2 are just too heavy and big to make sense. I'll bear the weight and bulk for the 70-300L because it does so much. The 50 1.8 and the 50 1.4 are both too flaky in terms of both AF accuracy and build. In the last 18 years I've had 3 canon 50mm 1.4 usm lenses each with problems and none with consistent AF.
I'm not a sharp corner snob when it comes to a 50mm and the canon 1.4 is plenty sharp when the focus hits and it isn't in for repair. I'd be happy with the exact same optics and real ring usm focus.
I'd also be content with a canon(or Sigma) 50mm f2 IS that was up to the standard of the canon 35f2 IS or 24f2.8 IS. I'd be downright giddy with a canon 50mm f 1.8 USM IS. It doesn't have to be an L. Just optically good with a reasonable build quality.
Tom





