iphone 4--should I get the 16g or 32g?

If you're planning on using it for video/photo use, I'd suggest going with 32GB. It'd be better than getting 16GB, and regretting it later. Video can take up a bit of room on your phone.

Also, this would depend on how often you'd Sync and play around with your libraries. You can always move things off/on the iPhone in iTunes. I personally have a 16GB iPod touch, and it's not enough for videos/pictures. I have about 4GB of pictures and about 6GB of video. I'm almost 3/4 full already. I'll welcome the larger storage space that the iPhone 4 offers vs my iPod touch.

Just my 2 cents.

Video takes up a lot more space than most apps and music. Especially because this new camera takes 720p HiDef movies. I imagine the pictures will take up some major space as well. 3 DVD's is a little under 16 gigs...If you don't plan on keeping the video on your phone for long periods of time, then 16 gigs could work well for you. I have a 16 Gig 3G and have over 400 pics, a lot of apps, and the rest is all music. It's completely full. With no video. I'm upgrading to a 32g because I need more space especially for video taking and editing. I rather be safe than sorry.

If you're someone who likes to dump files onto your computer, 16 GB would be fine. If you are not into taking video, 16 gb would definitely be fine. If you want to leave a lot on your phone though, I'd go with the 32.