I use the Palm TX that I originally bought for work!
It has Wi-Fi, and the external memory card.
The Wi-Fi is usable but will never beat the real estate of a laptop screen!
I mainly use it along with cachemate to hold a number of caches, along with the descriptions, hints, co-ords, and the ablity to edit in the field what items were taken or left! (handy if you do multiple caches per day!)
(The older you get, the more you forget! )
It also will allow you to use DeLorme Street Atlas Portable to get street level maps for any areas you can load to your external card!
It will also read the Topo maps from DeLorme as well!
I currently have the Topo map to the Morristown, Tn. area loaded, along with the caches in the area, and they show up on the maps as well!
Also have purchased and use GSAK as well! (Great little program)
GSAK is used to convert pocket queries to a form that DeLorme can read!
Hope this helps!
BlAcKrOk