I take the historical route 80% of the time and have it so well rehearsed that I should stop as it feels like cheating now.
Air is the key. Have two airforces - one TAC heavy ( 8 TACS) and one Close Support heavy (8 Stukas).
Begin your air operations a few days before you start the ground assault with the TAC airforce - logistical bomb Mullhouse, Strasbourg and Chaumont down to less than 20% infra. This will mean the forces there will be unable to move to where they are needed.
Punch from Cologne through Bastogne and Arlon with 9 Panzer and motorized divisions. Move Fast! Attack Reims while softening up with the Close support/Stuka airforce. You should be up against a fairly weak force of survivors from Arlon.
On the north flank of your center drive hit Liege hard - (while driving through Arlon/Bastogne with your main tank force) - I drop paras here with some tanks and infantry lead by a fortress buster and take Liege ASAP as it will give you another angle to attack Reims if things get sticky as well as providing a flanking position for you northern drive on Brussels etc.
On the southern flank of your center drive hit Luxembourg hard with infantry and anti tank stuff - the French always commit a lot to defend Luxembourg and along with your TAC bombing of the above mentioned provinces this will deny the French the troops they need in and around Reims.
Once you are in Reims with your main tank force open the hatch of your tank and enjoy the ride to the Channel.
This is in fact a fairly realistic recreation of what actually happened including the Para drop on the Fortresses around Leige.
Just remember to save your two airforces only for the missions listed above at first - dont burn them out unnecessarily on other targets. After you have Reims then turn them to other targets. I have a third air force for the northern part of the campaign.
The Luftwaffe is best used en masse on select targets. Take a close look at the map in terain mode and you will see why logistical bombing Chaumont i particularly important for bottling up the French forces - the alternative routes are full of rivers and hills.
Happy Blitzing!

(easy once you have tried it a couple of times - just watch for bad weather though)