1. Get a palm OS model. They are easier to use, there is more software, and unless you really need a portable computer you'll be happier with a palm.
2. Get either the tungsten or a sony CLIE. Go to a store that carries them hold them in your hand, see how they feel to you, see how you like the look of the screens, etc. My needs are similar to yours (except I have no need for e-mail) and I've ben quite happy with the sony CLIE T665. This model is being/is phased out. Given your needs you will be fine with one of the lower model CLIEs. I haven't kept track of the model numbers, but I think the one you want is the S20 or S30 (or is it now S33?).