Originally Posted by VegasGambler

Your don't have any stopovers, so they can certainly reroute you through different cities.

But of course you can refuse a rerouting. Technically if you can't agree on a routing your only options might be to accept what they offer or cancel, but in reality they tend to be flexible about this sort of thing. Before your trip, find acceptable alternatives so that if something happens you can just suggest what you want (be ready with flight numbers)

One thing to keep in mind is that if they're is a flight cancelled there are a lot of people to reacommodate so your first choice might not be available. It's best to call in as soon as you know there is an issue -- you have a better chance of getting your first choice.