Which iPod is best to use alongside iPhone

[Terror-Inferno]

At the moment I use my iPhone 4 for everything and as my main music player, so the battery isn't lasting long when I listen to music throughout the day. Because of this I was thinking of getting a iPod as my dedicated music player instead.

At the moment my music library is about 5000 songs at 30GB, so I've narrowed my choices down to:

• iPod Nano 16GB - 4th, 5th or 6th (really like the small size of the 6th)
• iPod Classic 80GB

But this is as far as I got with picking just one,

I didn't know if the iPod Classic would be heavy to carry along with my iPhone or if the 16GB Nanos would be enough space for most of my music (compressed to 192 kbps or lower).

Any help to narrow my choices down a bit more would be very helpful,
thanks,

[Ariii]

You should get an iPod classic... if your music collection grows, you're going to end up upgrading from the Nano soon.