The floaty boat-like feel is a result of soft springs and dampeners. Adding lowering springs (typically higher spring rates) reduce the floating feel a bit, but proper dampeners (tuned for sport instead of comfort) well tame the float. Sway bars by themselves will not cure the float. Where sway bars come in is when you're turning and feel the car plow and give that roll over effect. Upgrading your bars to larger (torsionally stiffer) will aid in reducing your roll center, thus causing the car to corner flatter.
If you already have DDC, then your shocks are electronically controlled and can be stiffened by just selecting Sport or Sport +. You then need only to add lowering springs to control float and sway bars to control roll.
There is also the coil over option that upgrades springs and shocks all in one shot.
Several solutions out there depends on what you want and how much you want to $pend.