My favorite Sig P320 configuration, and by far the best value IMHO, is the P320 Full Size Tac Ops. It usually retails for around $70 more than the standard P320 full w/ night sights and has four 21 round magazines, and a TFO fiber optic / tritium front sight. Can sell two of the 21 round mags for $100, buy a 17 rounder for versatility, and come out cheaper than the base P320 w/ night sights that only come with two 17 round mags.
$650 base P320 Tac Ops
-$100 (two 21 round mags)
+ $35 (one 17 rounder)
$585 total - same price as base P320 but you get two 21 rounders and the TFO!
I really love the contrast between the bright green TFO front and the standard Sig night sight rear. Makes the sights super fast and easy to pick up!