Having gone through the process myself with a 1-yr old growing to 4 now, I thought the 17-50/55 range fit better than the 24-105, especially considering you have a crop. With a toddler, you're always not too far, so you really don't need the longer range, and I think the 17-23 range would be more useful indoors and with group shots that you'd need with family get-togethers. The f2.8 also helps with indoor shots when you don't want to bother with a flash or just want to be incognito with your shots. The 24-105 fits better on a FF.
right, the Tamron 17-50 2.8 will be fine indoors especially with a flash, moving kids (or dogs!) are not a problem. F2.8 really helps with indoor pics




