I'm going to go with "2D images."
In most situations, you don't change perspective enough to benefit from a 3D model of Earth. And finding nice 2D images should be easy.
Of course, it depends on how far away you are and how fast you are moving.
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iClone6 Pro, and 3DXchange Pro
Homebuilt computer - Windows 7, i7-3770k CPU @ 3.50GHz, Radeon HD 6850 Graphics, 16GB 1600 MHz RAM, Asus P8Z77-V Pro motherboard, 240GB OCZ Vertex 3 SSD, terabytes of disk space, and dual 28" monitors.