The OP's post is...really rather confusing. First he/she asks for "Full suspension on front and back" then..."Prefer a flat-bar commuter type bike over MTB"?
I can only completely agree with "HandsomeRyan" - rear suspension will do nothing for you but have lots of drawbacks. From personal experience to - I've ridden around with my dad (who likes a much more relaxed pace ride, thus the reason for the mountain bike on the road) and that rear suspension will absolutely *kill* your efficiency. I was having trouble keeping up with him, even working hard!...then I locked out the rear suspension, and I was back to needing to take it easy not to outdistance him. It's a *severe* difference in speed and efficiency. It's probably different with the really expensive rear suspensions...but we're talking like $3,000-$5,000 bikes.
If you're only doing road use, I personally see very little benefit to *any* suspension at all for pure road riding, even on terrible roads. Obviously you want a plush ride, but I would highly suggest a commuter type bike like you Giant you linked to, but put big cushy tires on it (slicks will also be more comfortable, and have more grip for on road use). I specifically suggest the Schwalbe Marathon Supreme's (the "Supreme" part is important, Schwalbe makes a lot of other "marathon" tires) in a big cushy (50c/2 inch) size. Make sure the bike can take tires that large, though, before you buy it (that's standard mountain bike tire size, but some silly commuter bikes don't have the clearance for good size tires).
In the interest of covering all bases, I do know of exactly one rack that will mount on a full suspension bike - the Old Man Mountain, Cold Springs rack -
http://www.oldmanmountain.com/Pages/...ar_gallery.htm
