These are just my personal thoughts. Not trying to be influential, but maybe something to think about.... While shooting my dogs, I prefer a longer focal length because as mentioned earlier, I want to capture them being 'them.' Running, playing, being themselves, whatever. I don't want to influence them too much. So I prefer the longer focal lengths. If I am too close, as soon as I kneel down, they want to run to me, say 'hey,' tackle me, or whatever, and those close shots aren't as flattering.
As for the IS vs. non-IS. I had the 70-200 f/4 IS. When I looked to move to the 2.8 version, I considered the non-IS version. But in the end, I didn't want to find the situation where I was looking back wishing I had spent a little extra on the IS version, and wishing I could sell and upgrade yet again. Also I didn't want to be in that situation where I wish I had it. Its one thing to want a different lens, but to what another version of the same lens is difficult, because it makes it harder to justify upgrade. You would already have most of what you want, but would just be missing that last little bit. So, my advice, if you can swing it, save the little extra and get the IS version. You can always turn it off, but it certainly doesn't hurt anything. I don't shoot in low light often, and mostly shoot sports/action with it at high shutter speeds. And though you say you are a nice weather shooter, you never know when you might be out in the evening, or it may not be 'bad' weather, but maybe cloudy, and you want that little piece of mind.