I see a lot of tutorials for UV mapping planets but they are mostly in cycles. Does anyone have any suggestions on the best way to UV map ( or some other kind of mapping) planets so that I can fly around them in BGE and look at them from all angles? Thanks!
Well, there’s the Sphere Projection option in the UV editor… It unfolds a sphere like you see in old atlas maps where the map is cut vertically and split near the poles so that it can wrap into a globe.
UV mapping is the same whether you are in cycles or the bge. You should be able to use any Blender uv mapping tutorial to help you with this subject 
Heres a nice planet uv mapping tutorial for blender - https://www.youtube.com/watch?v=dBc3VS0RbB8
but as mentioned earlier… a spherical uv unwrap should to the trick for this, although, when using a UV sphere mesh, there can sometimes be texture distortion at the top and bottom of the sphere where the mesh is all tris