My dog gets adjusted every two months or so for routine maintenance (he does agility so having everything in place is important). He also has a lower back problem, so keeping it loose is also really important. The chiro watches his gait first and adjusts his whole body, focusing on problem areas.
He's had acupuncture for various things, but he's not really thrilled with it. The vet does B12 shots along with it, which is what I think he hates about it. So now he doesn't even want the acupuncture needles.
I think both can be really helpful for lots of things.