so I figure it would be easier to roll one big suitcase weighing 100 lbs., rather than trying to manuever two luggages on wheels weighing 50 lbs.
... True enough, unless you happen to be the poor sap of a ramp worker who has to lift that bag into the cargo hold of the plane. THAT is the reason for the weight limits on individual bags; too many workers' comp claims from ramp workers from lifting overweight bags all day.
You don't have to manuever two suitcases each, as long as your large bags don't exceed the 62" size limit (if they do, then retire them for air travel and come down a bit to nothing bigger than a 29" pullman"). Get yourself over to Target or similar, and buy a mid-sized cloth duffel that will set you back about $14. Put a luggage tag on that duffel. Pack your rolling bag with space bags that will allow you to get more into it, then put the 2 or 3 heaviest space bags on the top, along with the folded duffel.
When you arrive at the airport, get in line to check your bags, and when you step to the counter, unzip your pullman and take out the duffel and 2 or 3 space bags. Put the space bags in the duffel, zip it up, and hand over the duffel and the wheeled bag. At the carousel at your destination, reverse the process. Voila! You didn't have to maneuver two wheeled bags anywhere. I've used this method in more countries than I can count, mostly when I needed to push a stroller with the other hand. (The key is that you MUST use at least some interior bags in the rolling suitcase; you want to be able to switch about 1/2 the weight very quickly into the duffel without dropping stuff all over the place. Done right, packing the duffel takes less than 60 seconds.)
Oh, and I agree with Anne that you should lay everything out on the bed before putting it in suitcases, and do put half of your initially-planned stuff back. When I take my one 29" pullman to Europe, I'm usually packing it for 2 adults and a child, for 18 days in winter.