I'd also recommend one of the 70-200s as a much more versatile lens. You will not find many pro Canon shooters who don't have one in their camera bag. Any of the four versions (or the recently discontinued f2.8 IS "Mark I") is a real workhorse of a lens. Great image quality from them all, so that's not a big concern.
If most of your shooting is outdoors in daylight, the f4 might be plenty of lens. If possible, go check them out in person. The f2.8 is a much larger and heavier lens, in addition to more expensive. For the greatest versatility, get one of the IS versions. Some will tell you that IS isn't necessary for sports or fast moving 2 year olds, but it's always nice to have, IS can help even at higher shutter speeds, and a lens with IS just opens up more shooting opportunities.
Only Canon offers f4 versions of 70-200... and that lens doesn't come with a tripod mounting ring. It's up to you, whether you want one or not. The f2.8 lenses come with a tripod ring. If you get an f4 version do decide you want a t'pod ring, check out the 3rd party clones on eBay (and at some of the major retailers). They are much less expensive than the Canon tripod mounting ring.
One possible reason to want the latest 70-200/2.8 IS Mark II version is if you think you'll want to use it with teleconverters. The earlier models work well with 1.4X, but not so great with a 2X teleconverter. The newer lens works very well with both, especially the new Mark III teleconverters. The newest lens also has more effective IS and improved bokeh. It's a very nice lens... only you can say if it's worth the significatly higher price, extra size and weight. I still haven't "upgraded" from the "Mark I" I've been using for around ten years.
If you have a yen to do occasional macro, simply get a set of macro extension tubes, such as the Kenko. Those can be used with any lens, to make it much closer focusing. Canon sells individual 12mm and 25mm tubes, but personally I think the Kenko set is a better value (the set includes 12mm, 20mm and 36mm). Following was shot with a 25mm tube on my 70-200/2.8 IS:
EF 70-200mm f2.8 IS lens, EOS-3 camera. Settings unrecorded. Ektachrome E100VS film. Gitzo 1325 tripod with Kirk BH-1 ballhead. Fill flash, 550EX. I was set up alongside a stream to shoot egrets, and noticed this guy almost right in front of me, so quickly changed subjects. Didn't have a macro lens with me. But I always have macro extension tubes, just in case. Never did get any good shots of egrets that day! Magnification is probalby one third to half life size in this shot (approx. 1:3-1:2 or 0.33X-0.5X). It was a pretty large spider, though a whole lot smaller - and friendlier - than the tarantulas we get around here. Without any extension tubes, depending upon lens model the 70-200s can do between 0.16X to 0.21X on their own (all at 200mm, 1:8 or 1:5 approx.)
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