Maemo Mapper seconded as your best bet.
I've got street view maps of a few big cities, most of the motorways and my home town, from both google maps and the odd bit of google satellite view in about 179 MB.

http://maemo.org/downloads/product/OS2008/maemo-mapper/

The only problem might be in browsing by street address - in order to look up streets / postcodes it consults an online directions server.

I believe that you can use routes from other software with it - so you should be able to keep them off-line.