This model is based on survey data from the excellent HRSC MOLA blend, which you can find on the USGS website. (Yes, that really is a single .tif holding 11 GB of data)

The heightmap has been exaggerated to show every surface feature very obviously (not that Mars needed it).

I have included three surface textures in the blend file:

1. A color-coded heightmap I created from the HRSC MOLA blend
2. A map compiled by NASA from Viking orbiter imagery
3. An edit of the Viking map showing a terraformed Mars

Unpacked, the blend file is roughly 350 MB. Let me know if you need a lower size version.