We have *not* done this, but have really thought hard about it. What held us back was that we wanted to offer DVD players in rooms and did NOT want to put a component on a shelf or piece of furniture, and at the time, we could not find Flat panel TVs that both had built in DVD players and the internet capability.
*We* use it (internet streaming) all the time. In fact, if it weren't for the BnB guests (and a few sporting events LOL), we would ditch the satellite altogether.
I am curious to hear how you feel it works out.
BTW - I sort of inquired with Netflix about this (it wasn't about the BnB, but similar situation) - you can stream up to three selections at once to three different devices (TV, computer, whatever) at the same time on one account. I expect they are not thinking people will use this in BnBs. Something to consider: People will be accessing "your" queue. Our previous device did not allow us to alter the queue from the device, we had to go to the computer. Our current device will. So...if you were making your account available to guests, either you'd need to pack your queue full of an eclectic list of movies (perhaps crowding out what you want to find quickly), or you might find things you didn't really want to watch (that they added, if your device permits it), AND...if you are in the middle of watching a series, and they watch the next episode...Netflix will mark it "watched" (DH and I have been watcing series, esp from BBC, one episode after another - this would mess us up!).
The deviced we have used (wii and some sort of Blue-Ray player...DH's domain, not main) do not store the password. They have to be activated using a (separate) computer access to one's account. So no guest would be able to access our account profile/information after using our Netflix access. But I don't know if that's so with all devices.
I will say, I know we have had guests who have opted, rather than watch TV in the living room or watch a DVD to stream video (usually a TV episode they missed and were catching up on) on their computer. We have dsl, very rural but still in town such as it is, and no problems whatsoever. FWIW, at the time, we had the slowest speed available (we've increased that for our own purposes).