Pondering on the worst case scenario here... :lol:
The worst case scenario would be if Dennis moved WNW, at Cat 4 strength, and it hit the area just west of Slidell. The area from Slidell east to Pascagoula would be devastated by the surge from the GOM, and the area around New Orleans would be devastated by the surge from Lake Pontchartrain.
On the other hand, looking at my atlas, another "worst case scenario" would be if Dennis moved just west of New Orleans. The strongest winds would move over New Orleans, but more importantly, surge from the south would as well. (if you look at an atlas, the GOM isn't that far from New Orleans). And, of course, the Slidell/Bay St. Louis/Biloxi/Gulfport area would still be inundated.
If Dennis hit the Pensicola area, it would just add to the devastation in that area already. If it hit Mobile, the surge from Mobile Bay would devastate the area.
:roll:
The best area to make landfall would be near the rural marshes of central Louisiana, Kenedy County TX (not likely), or the rural "Big Bend" area of Florida (around Perry/Taylor County FL). The latter area has a special bonus: waters are a bit cooler there; just look at the SSTs.