The Glock 22 is the full-size .40, you can put the Glock 31 barrel in it to switch to .357 SIG. To switch to 9mm you'll need an aftermarket barrel like the ones made by Lone Wolf.
I prefer the Glock 19 (it's my current EDC) because it's a little more compact than the 17 but still feels and shoots like a full-size gun. I also prefer the 9mm but the .40 is definitely more versatile.
The 34 is a fantastic gun for target or competition and it shoots amazingly well for most people, but the long mag release, the adjustable sights, and the long slide make it less good for carry.
Gen 4 Glocks all have the new dual-recoil spring (previously only the 26 and 27 had them), they have adjustable grip backstraps (normally the grip is slightly smaller, but it comes with two panels you can pin on to make the grip either the same size as the Gen 3 or slightly bigger), the grip has a more aggressive texture, and the mag release is bigger and more easily reversible.
0331: "Accuracy by volume."