I have a Sig P220 Elite Stainless on layaway now. It's DA/SA and both modes are very well executed. Good choice!

First, just want to say welcome to the forum, there is a lot of information here.

Second, I have to ask, have you tried any firearms at the range? If not, lets talk. The Sig P220 is a great handgun, I own one. However, it is a .45ACP caliber. If you've never fired a .45, find a range that rents handguns and go fire one first.
Why? Well for one, the .45 does have a good amount of recoil to it. Especially when you're talking a smaller frame like the carry series. Learning to shoot a handgun by diving into a larger caliber like that is like handing someone a 7mm Rem Magnum rifle and teaching them to shoot with that. They can get a few rounds off, sure, but for someone not used to that type of recoil it can teach a whole bunch of bad habits straight from the get go.
Personally I would start off with a good .22 or 9mm, less recoil to start with, but great calibers and still some great firearms to start off with.

.22 recommendations include:
Browning Buckmark
Ruger MkIII
Sig Mosquito [new only, the original run had issues with the slides]
Beretta Neos

Popular 9mm choices:
Beretta M9 or 92FS
Sig P229
Springfield Arms XD9
Smith and Wesson M&P 9mm
Ruger P89
Glocks

As far as DA/SA vs SAO, I'd prefer a DA/SA

Welcome to the forums, have you considered a polymer frame Sig. There second to none in quality,looks and reliability. Not to mention a brand new 2022 can be had for @ $475.

For a range only gun I would buy a SAO due to the crisp tight lighter pull trigger. For protection I prefer DA/SA. I have shot a few Sigs and liked them all however I have never shot the 220 so thats about as much advice as I can give on the subject.

Great forum!

Thanks to all of you for your opinions, recommendations, and support.

I was able to look at some more Sigs yesterday and since this is a first handgun, the recommendation to start off with something that is a smaller caliber was right on. The recoil of the .45 is an important consideration in regards to developing bad habits at the beginning of my learning curve.

I'm now leaning towards the Sig P229. I like the idea of SAO (since it's primary use would be target shooting), but (I think) it is a better choice to get up to speed on the 9mm of the P229 and learn on the DA/SA trigger.

I also like the P226, and it would probably be a better choice since the sights are her apart, but I wanted a slightly smaller handgun (just personal preference). I'm really looking forward to increasing my skills and knowledge.

Thanks again for everyone's help.

Welcome from Big Sky Country.

Congrats on your new purchase.