If, on the odd occasion, you really do need that extra 2mm ... can you not just walk backwards a bit? It would be cheaper and easier.
I could manage quite happily with the 18-35 and 24-120, with a couple of faster lenses for indoors - 28 and 50. But those lengths suit me. Some people like the wide angle look. Others find it artificial. It all depends on what and how you shoot if certain lenses will suit you.Thanks for the comments so far, in real world terms when would you say 16 is preferred to 18? I like the idea of being able to shoot ultra wide but haven't really had any experience with this. I have the 24-120 f4 and I'm also curious if 18-35 would compliment that lens?
I could manage quite happily with the 18-35 and 24-120, with a couple of faster lenses for indoors - 28 and 50. But those lengths suit me. Some people like the wide angle look. Others find it artificial. It all depends on what and how you shoot if certain lenses will suit you.
I know it's heresy on here to suggest Ken Rockwell might ever offer good advice, but in this case I think he has - http://www.kenrockwell.com/tech/how-to-use-ultra-wide-lenses.htm