You can't go too far wrong with a P226.
My P226/40 has gone through almost 10,000 rounds without choking once, and it's way more accurate than I am. The standard bar/dot white sights are suprisingly visible in moderate-to-low lighting (way better than straight steel), but at night you'll definitely want tritium.
The DA/SA trigger takes getting used to; I recommend shooting pairs (one DA, one SA) to get the transition nailed down. Once you've mastered that, it's no problem. Both the DA and SA pulls are very nice. There's also the SRT (Short Reset Trigger) that doesn't alter the pulls much, but reduces the reset on the SA considerably. I've heard mostly positive, but haven't tried it. I haven't worked out much with the DAK trigger, but I've tried it in a store; it's quite light for a DA, and noticeably shorter than standard DA.
You mentioned the metal frame. The standard 22x guns are aluminum alloy, while the ST series have stainless frames. The slide is actually heavier the frame with a standard gun. If you want more weight to soak recoil with, the ST is good, but aluminum seems to work just fine.
.45 is plenty accurate, by the way...it's the de-facto caliber of bullseye shooters, who punch 2" groups at 50 yards, and the P220 is one of the most accurate out-of-the-box guns. Bigger calibers recoil more, and therefore there's more possibility of developing a flinch or anticipation, which messes up accuracy. There's also some rumors of inaccuracy about the M1911 that resulted from people shooting worn-out guns (no 1911s were made after WWII for the US Military, and they were issue until 1985, so they got shot a hell of a lot).
