You're lucky. I really, really wanted to have a system including Wides but I simply don't have the space to install those speakers at the proper locations, so I had to eventually settle for a 7.2.4, which isn't bad anyway because I could setup those really well.
My Blu-ray is on the way, will review the Atmos mix soon. I'm very familiar with the stereo and 5.1 mixes - it's one of my most listened to albums in the last few years (35 spins from start to finish according to my last.fm, plus a few more of some specific songs).
If your room/setup doesn't call for it, you're not really missing anything. I've gotten to experience wides in various rooms. If you have a large gap to fill between the fronts and rears along with speakers that don't have a wide soundstage, they are excellent additions. If your front speakers throw a wide soundstage and you don't have a discernable gap in the front to rear imaging, they tend to be superfluous.