Need more tracking!

[pxefig]

Hey, all! This question is for a non-Disney (*gasp*) race, but I'm hoping you'll find it in your heart to answer anyway!
I will be running my first full marathon in December and I'm guessing it'll take me right in the six-hour ballpark to finish. I use the runkeeper app on my iphone 4 and I am realizing there is no way the battery is going to last that long! What are some good options? What would extend my battery life? Some battery extender?Or is there a Garmin watch recommended?
I like having my music when I'm running but I'm sure if I am using my phone as a music player and not using the GPSt tracking app the battery will last the whole time. A GPS watch would certainly be nice, and I guess my requirements for that would be that the battery would last longer than six hours, and that it displays current pace, average pace, overall distance and overall time.
What are some recommendations?
Thanks!

 

[Raenstoirm]

Most races will not allow you to use your own music now-a-days. My half marathon next month says no personal music players or headphones. I think it is a safety thing. So that might not be an issue with your battery life.

I too am looking into a running watch, so I am anxious to see what everyone recommends.

 

[pxefig]

Yeah, the headphones was something I made sure was allowed before I signed up because I think I would go crazy not being able to have them! Their website has the statement: We expect all participants to use good judgment and take responsibility for their actions should they wear an iPod or similar device during the race. We do ask that all participants be able to hear last minute instructions both at the start and finish lines, and that the ear buds be removed at these locations.
So that is good to go. Now I also need to make a playlist that will last that long!

 

[bumbershoot]

My brother loves Garmin products, and their site shows battery life for each of their products. You wouldn't want to get the 10, but *maybe* the 210?