The 8" and 10" Wagner Ware skillets in the second link are very nice. The little #3 in the first listing is tiny. If you wanted to saute a bit of onion and garlic for a dish, you might use it, but a #5 Griswold is the smallest I would get, since I'm a cook, not a collector. It's a good size to do up a couple of scrambled eggs, and it's almost always on the stove-top waiting for another task. Lots of savory/aromatic stuff starts out in that little skillet before being added to the sauce-pot.
If you get the 8" and 10" skillets, start haunting lawn sales and estate sales and see if you can come up with a 10" dutch oven and lid. The lid can do double-duty on the skillet and the pot. My wife and I have a 12" dutch oven with lid, and the lid gets used on our 12" skillet quite a bit. It holds in both heat and moisture, with is really nice when you're whipping up a risotto or something similar.
Griswold and Wagner Ware are both good high-quality brands, and the cookwear lasts lifetimes. Invest in some non-scratch spatulas, so you won't erode the cured surface of the cast iron. If you need to clean cast iron and stuff is cooked on, the best method I've found is to put water in the pan and bring it to a boil to loosen the tough stuff and de-glaze the pan. Wipe out the pan with terrycloth or a nylon scrubber, then scour the bottom lightly with coarse sea salt, wipe that out and lightly oil the pan with oil with a high smoke temperature (I use peanut oil) and reheat the pan. When the pan is cooled, wipe out the excess oil and store the pan.
You don't have to do this whole routine very frequently - just when the pan needs a real good cleaning. With a few years of seasoning, the bottom of the skillet will be shiny and practically non-stick.