My iPod Touch and original iPad are both 32GB and are near their max. Have to manage content. Today I would buy the largest possible, even a 128GB if they offered. So when upgrading the iPhone last month went with the pricy 64GB. Thought was the iPhone was the iDevice I would have with me constantly, taking a walk, shopping, travel. Others not as often. Wanted room for apps, GPS apps, audiobooks, music, movies or two, iBook/Kindle books, lots of room to take and play with photos or doodle. For the extra $100 wanted the room for possibilities.
Another option if you run short of space is something like the iPhone size Kingston Wi-Drive. It can hold music, video and photos and share with other iDevices. Price is dropping. Look at Amazon to see the info and reviews. There maybe other similar devices.
-- My iPad has more video and drawing apps and drawings, more books, visual items. The Touch is more sound leaning. The iPhone does have the small screen, but you have it with you all the time so with the exception of something like taking handwritten notes it does everything the iPad does.
Another POV for your consideration.
