If those are the main things you'd use it for, then yes, switch to the iPad. It will do the things you want with some advantages and with no sacrifices for your desired uses (music in car and on plane).
Oh yeah it is definitely worth it. Your gonna need an ipod nano or something, but if your just looking to to upgrade the touch, its a worthwhile addition. I am hoping that OS 4.0 will add alot more functionality to it, but if you are cool with having a different mp3 player to carry, unless you want to carry this around or your phone, then its a worthwhile upgrade. I upgraded from a 64 gb touch to a 64 gb ipad, and the extra screen is awesome the apps, games, etc.