First of all get the super sweet corn, such as the kind with the bicolor white and yellow kernels. It holds up much better to the indignities of mass preparation.

To Steam Corn on the Cob
Remove husks and silk from fresh corn and place corn upright with the stem end down in large kettle with one inch of boiling water. Cover. Steam until corn is tender, 6-10 min., depending on maturity. Corn should turn from creamy yellow to a brilliant, transparent yellow.

Boiling

This method works well when cooking larger quantities of corn on the cob.
Take the husks and silks off your corn.
Add enough water to a large pot to cover corn when it is added. Be sure you do not have so much that the water overflows when the corn is added. Add a sugar to the water if desired.

Bring the water to a full boil and then add the corn to the water.

Allow the water to come back to a boil (this can take 20-30 minutes with a large pot) and then cover and turn off the heat. Allow the corn to stand in the hot water for 5 to 7 minutes. Do not overcook.

If you must hold the corn, this is the prep to use, hold it in the pot in the water, but not more than 20-30 minutes.

Remove finished corn from the cooking water and serve while warm.

I would experiment by making one pot-ful in the size pot I was planning to use, to check the timing.

Grilling/ oven:
Husks On

This method would be mare suitable for an outdoor or informal situation, as the eaters have to remove the husks.

Peel back the husk without removing it from the corn cob.
Remove the thin silk that runs along the kernels of the corn. Remove excess silk with a vegetable brush or with a damp paper towel.
Fold husk back to cover cob. Secure husk with kitchen twine, or just twist closed if not over-trimmed.
Soak the corn in water for 1 to 3 hours before placing on the grill or in the preheated oven.
Place prepared corn on the grill directly over medium heat.
Cook 20 to 30 minutes, turning frequently (grill) throughout cooking time.
In the oven, you do not have to turn. In the oven, each rack gets a single layer. It takes 25-35 minutes at 400, up to 1 hour at 325.

Corn is done when it starts to steam.
When done, the husks will be charred if grilled but the corn inside the husks will be sweet and tender with a nice roasted flavor.

Tips