Movies and Videos are what really eats up space. I never have enough space myself, but music doesn't take up much at all. It could also be that once you have one and unlock all that it can do - you will become addicted and want more. Something to keep in mind is that the operating systems that make the phone work eat up about a Gig and a half so your 8 Gig phone only starts out with about 6.5 Gig. The second 8 is pure space. My belief is - better safe than sorry. The monthly plan is not cheap and for all the phone can do I would pay an extra $100 and get more than double the capacity. Good luck!
Don