Which to use: Cartesian or Spherical?

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In my spare time I'm working on a computer game concept which is going to require me to do quite a bit of three-dimensional navigation in code .. moving objects through 3D space. I remember enough of my Jr. High trig that I could probably do this fairly easily using cartesian coordinates, but I'm considering the possibility that a spherical coordinate system might be both more accurate and/or more efficient to use (not to mention more stylish).

Unfortunately, I never did any spherical trig when I was in school, so not in a good position to evaluate the question. I've done a bunch of online research into the math, but all that I've found so far is either aimed at the wrong use (e.g. distance calculations are given for great circles, rather than straight lines through the interior of the sphere) or the formula descriptions start so far over my head that I've been unable to make sense of what they're actually doing.

So, I've come with two questions ...

First, does anyone have an opinion one way or the other which coordinate system is likely to be better?

And second, assuming I were to go with a spherical coordinate system, where is a good place to start educating myself? I'd be happy with either a good fundamental tutorial on the math involved in navigating through a sphere, or even just a set of plug-and-play functions with good explanations for how to use them. I'd need to do mostly simple things like find the straight-line distance between two points, but also be able to work out things like the elevation, azimuth, and distance from point A to point B as if point A were the origin (when it isn't).

Thoughts from anyone?
Thanks!