I travel A LOT and I haven't found a city that I can't catch whatever American sporting event I want.
Yes, but you don't want to/can't always run down to the local sports bar. Baseball is 162 games/season. Basketball and hockey 82. Football 16.
But the bottom line here for all the neg posters is that just b/c Sling isn't useful to you doesn't mean its not useful. $30 extra is annoying, selling apps per each device is pretty much the way Sling is advertised so it's not like Sling is misleading anyone. And $30 amortized over the course of the time you'll actually use the app its not really all that expensive, especially when you consider the cost, for example, of a single season MLB or Sunday Ticket sub.