I don't know much about you, but I'd suggest trying both the B17 and the B68 (for slightly wider sit bones). I suggest no "S" models, no springs.
You really don't need springs for distance riding on roads, even on dirt or gravel roads. Springs are nice for city riding with potholes, cobblestones, etc.

If you've never ridden a non-padded saddle before, you'd be wise to break in both the Brooks saddle and your butt for a little while before doing any really long rides on it.