To me, 100 miles is too many EV miles, and yet, at the same time, it is not enough. It is not enough in that I will definitely take trips regularily that are longer than 100 miles. It is also too many because most of my trips are not close to 100 miles and I would, thus, have to pay extra for the excess battery capacity that I don't have a use for and also get worse fuel economy because of the excess unused weight of the bigger battery. I don't know what is ideal for me, but 100 miles is definitely not it.
I think 100 miles is a good range to start with, knowing that it will decrease in winter, with A/C, heater, etc use. You also want some extra range available in the event you get stuck in a parking lot on the interstates. If I were a 2 car house hold (I'm a 1 car, 2 motorcycle one), and had the funds, I would absolutely have 1 EV and 1 Hybrid vehicle. In all honesty, even a 50 mile EV range coupled with a 50 MPG hybrid efficiency would fit me quite well. It also helps keep the excess weight from batteries down and gives a good range for most daily driving.
I'm right there with you, which is why I chose 100 mile range. Look at the Leaf and it's less range in reality. That being said I would be happy with 50 mile range, but 15 is too few for the extra cost for me.