Its been a few years since I've reviewed recent photos in terms of focal length. Since I shoot primarily with a 18-200mm zoom (I'm actually impressed with overall lens quality - it is a Nikon after all), and since the lens is a bit on the slow side (f3.5 at wide angle to f5.6 at full telephoto), I'm always considering a new, faster lens or lenses. When I returned from India in 2011 (its been that long!??!), I methodically when through the first 1000 photos and recorded the focal lengths, hoping that the vast majority fell in the 18-70 range or the 150-200 range so that I could direct my purchase at a narrower focal length range. Alas, the photos were pretty much an inverse bell curve, with lots of wide angle and lots of telephoto.
So, four years later, I've still got the same camera (Nikon D300) and lens (Nikkor 18-200 f3.5-5.6) as my go-to setup. And still toy with the idea of upgrading camera and/or lens. So, having recently returned from Morocco, I did the same recording exercise, this time focusing on the 350 or so best (or at least better) photos. And, again, ended up with a inverse bell shape. About 1/2 the shots fell into the 18-40mm range (actually 27-60 given the sensor size on the D300), and about 25% at various telephoto settings. So, if I were to stay primarily with one lens, I've probably got it already. Looking more closely, if I were to purchase a new lens, it would be at the wide-angle end of the spectrum, since they do constitute about 1/2 of my current work.
If you have a primary zoom lens and software (like Adobe Lightroom) where you can easily read and record focal lengths, I highly recommend taking a sample of recent photos and see whether you are primarily a wide angle shooter, a mid-range one, or a telephoto one. Or, like me, all over the place! :)