In reply to Brumbler:
Worth a shot!
You should ask yourself what sort of photos do I mostly take or want to take, and base your choice on that. I mostly shoot wide or very wide and that's why I went for the UWA. You get in close to see the detail or holds plus you get enough of the context to create a better cop.
Or do you prefer close up detail and tight cropping, in which case the 35mm suggestion above is ideal. I have the same lens and it's great, I just don't use it anywhere near as often as the UWA.
Flexibility, and it's a zoom of some sort, that you have just now.
What's your budget anyway?
Edit: what's the percentage split between shooting stills and video? Would that help determine your choice?
Edit 2: I should have added that my original suggestion was genuinely based on the fact that if it's mostly bouldering you're shooting, you're no doubt often in quite confined spaces, in which case a w/a is probably a sensible choice. But you really need to give us a bit more information before we can give decent suggestions.
Post edited at 21:53