Agree with the blu-ray superior picture and sound. Personally, I find the DVD helpful as the kids can watch the film in the car for example. Also I suppose companies are trying to steer non-blu-ray buyers towards the newer format. It saves them having to package the blu-ray and the DVD separately.
I find that having the double play is a nice benefit merely for the fact you can let someone else borrow the DVD! However concerning the triple.. well I've never ordered one but unless you can instantly download the digital copy it seems a bit redundant - most people nowadays have DVD copiers on their PC, and this gives the opportunity to choose file type, compression, etc.