I don't know about you, but I am always legitimately pissed off when I have to buy additional software on top of the bluray drive.
That being said, I always used PowerDVD. In years past I've also tried Corel WinDVD Pro and ArcSoft TotalMedia, but PowerDVD just seemed to work better in my opinion.
Although honeslty, I've started using AnyDVD HD instead and doing 1080P MKV rips with Handbrake first and putting them on my NAS, that way I don't have to mess with discs at all anymore. From what I hear, AnyDVD HD will allow you to play blurays in whatever program you normally use (I use Media Player Classic), but I can't confirm that since I already had the bluray playback codec from PowerDVD.
If that's the case, and AnyDVD does allow playback, I'd use that. It's an amazingly handy program, and adds so much more than just playback functionality.