Mr. Mark, no offense, but if you're having to "sand the crap" out of your work piece after hand planing, several things may be happening. 1)you may be trying to plane to deep at once, & leaving marks. 2) you're using a plane in dire need of a good sharpening. 3)possibly using the wrong plane for the job, or planing to fast. My experience with a hand plane is it should take very little sanding afterwards. You should end up with smooth surface.

Sandpaper can do more quicker than most realize. Depending on the wood, & I use all rough sawn hardwoods, I'll start with 100 grit, & finish up with 220. Sanding has its limitations, & every grit has it's limitations.