I like the 229, but given that a pistol is a quality made piece, whether or not you like it is going to be totally subjective. It is a bit thicker and heavier than some other pistols that I could carry. I like it enough and shoot it well enough to carry it anyway.
I like 357 SIG. However, I think all the defensive pistol calibers are about the same in terms of effectiveness: 9mm, 45 ACP, 40SW, 357SIG - some may have slight advantages over others in some particular situation, but overall I am certain there is not enough difference between them to justify all the debate over which one is better. They're all effective defensive pistol calibers, which one you pick should be determined by which one you shoot best.
The "relative unavailability" of 357 SIG doesn't affect me in the slightest. If you buy your ammo retail from gun stores, you're going to pay through the nose no matter what caliber it is. If you reload or buy in bulk, they're all about the same. Except 9mm, which is definitely less expensive than the other options.
If ammo cost and availability is a big issue to you, the 229 does come in 9mm or you can get an aftermarket barrel to convert your 357 SIG 229 to shoot 9mm (doesn't work the other way around - the 9mm models can't be up-converted to 40/357).
If I was thinking 229 in 9mm, I would rather get a 228 which is basically the same pistol but lighter and better balanced (becuase it doesn't have/need the heavy stainless steel slide required to shoot 40/357).
I prefer some brands of aftermarket night sights to SIGlites. This may have changed on the newer ones, but the older SIGlites were difficult to see in the daytime. The Trijicons that are basically the same thing have a larger white plastic "daytime" ring around the tritium lamp, so they're easier to see in the light. Lots of people on the SIGfourm like meprolights.
Unless you are really riled up to get the accessory rail, I would consider getting a SIG certified preowned and save some cash. SIGs are definitely durable enough I would not worry about buying a used one, especially one that's been inspected, freshened up, and tested at the factory.
One other thing - if you are a pistol "accessorizer," you may not like SIGs too much. There just aren't a lot of add-ons available (not that you really need any of them anyway, in my opinion). Also, a buddy who is the armorer for his SIG-equipped PD says almost all the reliability issues they have ever had were related to officers putting non-SIG aftermarket stuff on their guns. According to him, they run great if you keep them stock and if you do stuff the way it says in the factory book. I did once have problems with a SIG and it was due to a non-factory spring.
