HighPlainsPhotographer wrote in post #15761173
Having owned a 85 1.8, I found it too long for a general walk around lens on a crop camera. I would not be happy with it without shorter primes or a shorter zoom. Other than indoor sports, the 85 1.8 was not on my camera very often. Otherwise, a great lens. Fast AF and decent IQ, I did get some CA wide open.
I fully agree with this. I would hate to have only this lens on my camera. It's capable of producing amazing images, but on a crop camera it isn't particularly versatile. Indoors, in many homes it's too long to be generally useful for anything but head-and-shoulders-type shots. Also, it has an annoyingly long MFD, which makes it unsuitable for close-up work. On a crop camera, it shines for outdoor portraits and low-light sports, but I would by no means think of it as a general walk-around lens - far too limiting. Of all the lenses in my bag, if I had to choose one to sell, it would be this one. It's my least-used lens - although when I do use it, the results are stunning (apart from the CA in high-contrast situations). If you're not using your 50 mm prime, you're unlikely to use this lens either.
Given that you're doing a lot of indoor and low-light family photography, I'd have thought a Speedlite would be a better purchase than a new lens. Bounced light will do more to improve your indoor shots than a new lens, IMHO. And if you do decide to go with the 15-85, you'll also need a flash at some point.