I wouldn't run blocks unless you have to. My POS has 4" blocks in the back, and 2-1/2" add-a-leafs, and it axle hops somethin' fierce. If you do have to use them, you might wanna think about some kinda traction bar setup...
If it were me, Id probably get a shackle flip for the back, and a new set of stock springs
ORD sells shackle lift kits...interesting info at the very least:
http://www.offroaddesign.com/catalog/shacklekit.htm
for the front a 4" lift spring would be necessary...
According to the guys at C/K5, and Off Road Design, Tuff Country sells the softest lift springs. BUT they're after flex, not smooth ride. However, one would think that softer springs should ride better, within reason. My friend has TC 6" springs on his truck, and its pretty flexy.
I too, have heard good things about the 'Softride' springs.
My truck has 6" superlifts on it, and it rides like a jackhammer!!
-M