They are not really important beyond how loud they can go. The frequency response will be corrected by Audyssey. Floor standers are also not required. It's better to buy 4x higher quality book shelfs.
However the subwoofer is extremely important and you have to buy a good one. The AVR with MultEQ XT is the most important of all, especially with lower priced speakers and living room environments.
I am thinking of buying the following
Denon AVR-X1100W(for Wifi and multi room setup) / X510BT
Pioneer BS22(2 pair)
Pioneer Center
Sub(High quality-not decided yet)
Now the above combo should give me good 2.1 music right ?
Any other Bookshelf I should consider ?