I also find brighter speakers fatiguing with longer listening and I gathered that from your other posts that you seem to know that you like a warmer sound and that's why I recommended the Pioneers and the Ascends. Leave the lows to a sub preferably and leave the crossover between the speakers and the sub to the receiver and that goes a long way to eliminate that "muddying" you are talking about; aka a proper calibration solves this. Most receivers today are capable of doing this automatically to some extent.
The bookshelf vs surround thing isn't meaning 2 speakers will be better than a complete setup. If surround is the goal, then you can get 2 pairs of bookshelf speakers (or one pair of towers as in the package), the matching center and a good sub to achieve a very nice system. On a budget, you can start with just one pair and a sub and then add the other speakers as budget allows. If you want the whole kit and caboodle up front, well there's no reason not to as long as the funds are available
If your budget is higher, the people here can certainly help you find a smooth speaker within those limits too, I was just starting with something inexpensive and good and the Pioneers definitely fit that warm category to my ears.
The Mirages achieve that diffused sound, but they definitely aren't cheap. The nice thing about the Pioneers is that you can pick up a pair at Best Buy, listen to them and decide. If you don't like them, you have 30 days to return them.