Ah, just a straight ATP MEL. Expect to generate a flight plan from A to B. Expect to read through some METARs and FTs and NOTAMs. Do you need an alternate? How about if the weather was XXX/X? What kinds of airspace are we going through? If you were flying VFR what would we have to do to enter each type? Do a weight and balance. Here's another 50 pounds, where's the best place to put it? How much runway are you going to need? What if the temp was 15 degrees more? How much runway do we need at B? What if it's raining? Expect to talk about the signs and runway markings you'll see taxiing out. And you'll go through the SIDs, STARs and approach plates for the flight. Be able to talk about the maintenance records/inspections required. What would be different if you were going to fly this trip for fun with some friends v. doing it as an air carrier flight? Hey, a nav light is burned out, can we go? I could make all that last an hour and a half.
Expect to go over any areas you miss on the written. And know the limitations of your aircraft. If it's got GPS or glass be able to explain what it can and can not do, how you know the data base is up to data and the different modes of the glass.
I think I'd rather talk about the different temperatures that cause a pack to trip.