We currently use a car satnav, to get us to the start point then unplug and use it once near the cache area as the GPS receiver in it is fairly accurate and quick, it is for a car after all!!
We then use either a Android or Blackberry phone on which we stash all the GPX files, most apps will allow you to download a pocket query direct to the phone, save it to your SD card and use the offline lists when searching for caches. I currently run a 1000 cache file on my phone, it takes up suprisingly little space.
And anyone reading this in the UK, your about to get a GPS app for your phones that will allow you to upload, for a price, OS maps to your phone. (In BETA testing)
Halflings dad