You really need to listen to different speakers for yourself. What one person may recommend may not sound as pleasing to your ears.
For example, I personally do not like the sound of Klipsch speakers because I prefer a warm sounding speaker, i.e., Polk Audio, B&W, Canton. I feel horn speakers are a little harsh for my taste.
As far as whether a 5.1 or 7.1 is better, what size room will you be putting these in? If your listening area is right against the back wall, a 7.1 is probably not the optimum setup for you. A proper 7.1 setup, has the rear surround speakers BEHIND the listening area. Matrixing a 7.1 soundtrack to 5.1 is no big deal and you do not loose anything. I run a 5.1 setup because my room would never accommodate a 7.1 setup properly.
Since it sounds like you are going balls out for your first setup, have you considered separates? You could probably get into a very nice setup for the same price as that Denon you are looking at.
If your "gift" can be about $10-12K, I'm sure we can put together a VERY nice setup.
