When you book a hotel deal on groupon now, some hotel deals come up with what I call a built in booking engine. You pick the date and type of room, it shows you the price. I can assume booking this way books directly without the hassle of busting out your groupon voucher and calling the hotel direct. That always seemed like a bit of a pain to me.
I think it easy for the hotel too, because they don't have to set one price, which leads to extra restrictions and BS. You want to stay on a Friday no problem, here's your price for that night. If week is busier or slower they can have different prices set up.
I like this for if you are traveling and need a room, you can easily book and know its available.
Here is an example of what a deal looks like with the above stated feature. CLICK HERE
I admit, I haven't used groupon in a while for a travel deal. This always seems to be a slower time of the year for deals, but with upcoming travel plans I will keep this kind of deal in mind.