How often do you get an alignment?

[blktoptrvl]

So, I notice today that my left front is wearing the outer edge a little heavier than the rest, and I am about to embark on a trip to Key West. Alignment time!

So I go into a shop and ask for a price. They quote me $79, $109, or $159 depending on how long it is warranted - up to three years. I tell them I want the $79. They immediately go into a "up sale" pitch...

"Well you have a high dollar vehicle, don't you want the best?" I look at them funny.

"With the $159 service it is guaranteed for longer." I ask them, "are you going to tighten the bolts less for the $79 deal?"

They answer, "No, but if you hit a curb or..."

I put up my hand. "No, I just want the $79 service"

So, now I'm thinking to myself. The only two reason the vehicle should need an alignment more than once in a great number of years are:

1. I hit something - my fault, and I don't intend to hit anything. I don't encounter pot holes big enough to do damage (except for the one that cracked a wheel 4 years ago) and if that were the case the state would more than likely take care of that.
2. Something is wrong with the vehicle and the alignment won't hold. If that were the case I think I would have bigger problems than Alignment.

So, I wonder, how many people actually go for the longer guaranteed alignment? How often do you have yours aligned?