Iphone3gs:16gb or 32gb?

I have to decide on which is best for me. I have 10gb of music on my computer right now but I don't download music frequently. I have videos on my computer of a few seasons of shows but I'm not sure if that's something i need to watch right away. Im assuming once i have the iphone i will increase my downloading activity under both of these subject so im wonder if I should be conservative with the 16gb and just learn how to choose what I want on my ipod or get the 32 gb and not have to worry about ti. Another question is, will apps take up a considerable amount of space?