I have a 8 gb ipod touch, but I use an ipod shuffle for running.  I find carrying something like an ipod is enough to make me hold one arm differently from another while running, which can make me get uncomfortable pains in my shoulders.  The shuffle is so lightweight I barely notice it clipped to my shorts, and it carries more than enough music for even my longest runs.

Two things:

1) 16gigs is enough for most people. That'll hold songs (thousands), movies, photos aplenty. But if you'll have lots of videos, documents, or photos go for the 32.

2) Strongly consider an iPod shuffle. Personally I think the big iPods are too heavy to run with comfortably and I've seen a couple running friends' iPods bonk out because the repeated impact of bouncing while running isn't good for it. iPod shuffles hold enough for a run and are super light and not very expensive (especially if you save a bit of money with the 16gb Touch version.).

Enjoy!

16 gigs is 3500 songs.  32 gigs is 7,000 (or at 3 minutes a song 14 days worth of music if my math is correct.)

I think 32 gigs is overkill.  Even if you had 32 gigs worth of music, putting all of it on makes the shuffle featureworthless (IMO, because you don't really like a lot of the songs, so you are always skipping ahead), and navigating throught the artist is a pain because there are soo many.  Get the 16 gig, and save the points for something else.

But if this is going to be used just for running, the shuffle is better IMO.  I just set a play list before I go, and once I hit play I don't have to touch it until I'm done.

I own the touch and shuffle, and the last time I used the touch for running was the day before I got my shuffle.  My touch holds 8 gigs of music, and I only have about 4 gigs on it, even though my music library is much larger.  Since I only have songs I really like, I usually use the shuffle feature, and almost never have to skip a song.

EDIT:  BY recommending the shuffle, I recommend the 2nd generation.  Its 1 gig and it will hold 10 hours or music or so.

The 3rd generation shuffle is 4 gigs, but there are only controls on the headphones, which means if you switch the headphones (which you probably will since the stock headphones will not stay in when running, you will not be able to switch songs and volume.

If getting a shuffle Get this:

Not this:

I have iPod shuffle 1Gb, i bought it about 2 years ago, it was ok. I mean is still working but now i would to get a new bigger one.