Scott, you'll eventually wind up using both sizes - I'm talking rolls here. It depends on how you'll be packing your foods.
Personally, I pack 2- or 4-serving portions of (for example, fish) in cheap sandwich baggies, and then seal them all in a large (11-inch) FoodSaver bag cut to a length that will hold them all. That keeps them all together and I won't have to rummage through a freezer full of small bags that can get lost easily. For pulled pork or anything that I'll be heating in a pot of hot water, I'll portion into FoodSaver bags (usually cut from the 8-inch rolls) instead of sandwich bags but still seal them all together in a large FoodSaver bag or a Ziplock bag.
I've found it handy to slip a clean 3 1/2-inch diameter by 3-inch high PVC coupling into the smaller bags (sandwich or F/S) before filling them to hold them open. Then just pull out the coupling and slip it into the next bag.
Like Glenn, I always freeze my food before FoodSavering them to lessen or eliminate the loss of juices.
Others will have different systems, of course.
Rita