@dave get hold of any symbian belle device as it supports the 2xx version of map update ie richer data available transist lines etc...
It works fully offline
you can serch plan a route get waking driving predestian navigation with voice.
Only u will be limited if map data for said region isint good enough.
And modrana a good choice if you have time to prepare it for trip with various map sources overlayed.
Dont opt for sygic on any platform its very unreliable with jumbeld data wrong routing bla bla atleast for me in india
i found nokia symbian maps to be good enough for navigation combined with google maps offline java aplet in symbian to be perfect
now in modrana boat .