Ok, to those who are quasi-lazy...you want good textures, but don't necessarily want to make your own, but at the same time, you don't mind putting in a little effort...I humbly submit (not my own, but a finding...)
http://freebitmaps.blogspot.com/2010/12/srgb-planet-quom.html
The textures will need a little fixing size-wise, but they look pretty nice!
Also, can anyone out there make sense of this?
http://the-new-horizon.com/galaxy_map.html They show representations of planetary classifications widely used by Orion's Arm and ArcBuilders. It's a confusing read, but the samples look fantastic and quite inspiring.
Enjoy!
-M-