You have an iphone. Logic says ipad - too powerful for your needs, but unbeatable value otherwise as it gives you heaps of room to expand. Also, get the big one, more flexible than the baby. Well worth the extra money, not the least because you can get your phone calls/facetime calls on it.

The kindle, by the way, is the best of he readers, but even the most ardent fans will admit it is only passable at everything else. Then there's Strava, which, on the iphone/ ipad, is magic.