I have several P220's and love them. I don't carry them all the time but they all shoot well. The only reason I carry others more is they have higher capacity.
The full size have 4.4 inch barrels and the carry version 3.9". Since I OC usually the longer barrel length is fine and the carry version is still fairly large to CC unless you have a jacket or shirt to cover them.
Sig is a great name in the industry. I would also put H&K in the same league and those two are my favorite brands.
So out of the box you get accuracy, reliability, durability, ease of maintenance.
My favorite P220 is the Stainless Elite which is about 40oz. The weight helps with recoil/muzzle-flip. I recommend their night sites and short reset trigger (both included in the elite line). Since it is a single stack magazine 8+1, the grip is comfortable and thin compared to other brands.
As far as holsters, I like the SERPA retention holster. I have a couple leather holsters and picked up (free) a couple other plastic ones but keep coming back to the SERPA.
If you can, rent one and shoot it. The recoil isn't that bad and I find them very comfortable to shoot for long sessions which is not the case for some of my other guns. Extra mags are moderately priced compared to H&K's higher prices.
You can get a Crimson Trace grip laser but I would try one out first before buying. The activation switch is on the side of the grip as opposed to the front so pressing it and to keep pressing it can be challenging.
There are several different models and sizes. I prefer the full size 4.4 inch model the most but do own a 5" and a couple 3.9" models. The mags are all interchangeable between models except for the compact 6+1.
Breakdown is easy as is cleaning.
My only criticism of the P220 is the 8+1 capacity. While it is ok, there are other 45acp pistols out there that have double stack higher capacity magazines. I have a H&K USP 12+1, Para Big Hawg 15+1, FN FNP-45 15+1. With you being in CA I don't think it will be an issue for you until/if the laws are changed.
The only other thing that may be criticism is the price. At about $900-$1000 they are at the higher end of average users. There are many good guns cheaper but I don't find anything wrong with paying the extra price for something that is going to work and possibly save your life. :-)
If you buy one you won't regret it and you can always buy others too. Attached is a pic of my P220 Stainless Elite and Equinox (with threaded barrel).