The choice of Normandy was also decided by simple geography....The Netherlands and Belgium were low lying areas filled with canals and other water obstacles with most sites being on peninsulas, around Calais was too close to the Great Britain to facilitate the naval and air traffic....as well as being the heaviest defended and the Area of Operations for the 15th Army....and that left Normandy with nice sandy beaches and with sea ports close by.
One D-Day...the troops landing on Utah were swept about a mile away from their intended landing points which turned out to be a blessing as they landed at less well defended positions.
Some strategists were advocating not even doing Overlord and just waiting for the Strategic Bombing Campaign and the Russian's to bring Germany to its knees.
Churchill favored a Mediterranean avenue of advance and not doing Overlord for quite a while.
Other Operational Plans, amongst them Operation Rankin A,B, and C, were drafted ahead of Overlord which was an independent effort done by separate planners.
The US 101st Airborne Division was to be dropped into France to seize a seaport which would then be used to insert Allied ground forces should the German defenses be seen to be collapsing.
It makes one wonder if the Normandy Campaign with its tremendous losses could have been avoided had the Strategic Bombing campaign had not been suspended for the four months or so it was to support the lead up and immediate aftermath of D-Day.