Getting Off A Flight Mid-Connection

I spent a few minutes checking out flight options this morning, and came up with a bit of an idea. Here's part of the problem.

Option 1: Book Second Leg Later

Get a return ticket from Vancouver to Buenos Aires, possibly throwing the return ticket away in Buenos Aries and going somewhere else. The cost of that is about $1,500 right now, and then I still have to buy an expensive ticket to somewhere else when the time comes, which will probably be another $1,500. But at least I have a Vancouver ticket already booked in the event I want to come back.

Option 2: Use Houston as a Hub

Continental flies to South America, and Houston is their hub. I can catch a cheap ($150) one-way ticket from Vancouver of Seattle to Houston, and then book a round trip ticket from Houston to Buenos Aires. The total cost of this is around $1,300 (so cheaper than option one), and it gets me back in North America, where it'll likely be a lot cheaper to fly somewhere else, i.e. New York or Paris.

Option 3: Screw The System

I found a really cheap return flight from Vancouver to Buenos Aires via Montreal and Washington DC. The total cost of this flight is around $1,200. So, as a way to get back to Vancouver, it's $300 cheaper than Option 1.

I'm also thinking I could simply walk off the plane in Washington DC on the return leg, and forfeit the Montreal and Vancouver legs. Airlines don't really like this practice (they call it Hidden City Ticketing), but it's not illegal, and I can't really see anyone getting too worked up. I mean, if it cost more to change my flight than it did to buy a new ticket, the logical course would be to simply toss that ticket away, right?

So with this option I save a pile of money, have a guaranteed flight back to Vancouver, and also can get off in Washington or Montreal on the way home and possibly fly somewhere else. I'm having a hard time seeing the downside to it at this point.

Anyone?