You can find some great background raster maps for use in OsmAnd at the AnyGIS website. They are very easy to install into OsmAnd. You can download the whole set as a .zip file.
Download to your phone or tablet, extract if ZIPed, then click on the .sqlitesb file and open using OsmAnd. New maps will be added to your list There are a wide range of map types including satellite images, topographical, shaded relief and more.
We especially like Google Satellite + Labels and Google Terrain maps for use as an OsmAnd underlay map.
If you are ever on the ocean then Navionics Marine Charts are nice to have in your toolbox.
Just remember to pre-cache the tiles you want to have available on your device before you leave the warm comfort of a WIFI connection.