i use my phone as a gps so i'm not really sure what's good. He'll want something easy to use for walking and cycling. Built in maps would be nice if that isn't too costly. What is a good, simple, cheap one?

Not cheap, but the Garmin Dakota range is quite easy to use. All touchscreen based and can have maps on it.

I just got the Dakota 20 and put the free OSM maps on it (http://sites.google.com/site/talkytoasteruk/ukmaps). Haven't used it properly yet, but the maps seem decent…

hmmm… that looks nice. Probably a bit flash/pricey for my dad, though.