My grandparents, who were both Italian, always bought Fillipo Berio olive oil - in fact I always loved the big one gallon cans it came in, and used to clean them out and save them when they were empty.
DeCecco and some of the other expensive brands of pasta out there, I generally don't buy, since I don't see much of a difference in quality in the end product once cooked. Even worse, some of the pricier pastas are thicker, and end up taking much longer to cook. I don't recall my grandparents ever buying the more expensive brands of pasta - they were pretty tight with their money, and usually stuck with the more common brands, basically anything that was on sale. They would only splurge for certain ingredients. Not to mention, they would often make pasta from scratch themselves.
For cheese like Parmesan or Romano, never ever ever ever get those shelf stable, non refrigerated grated cheeses - always grate your own, or buy it fresh from a place that grates it fresh daily.
For candy, they were always partial to La Florentine brand Nougat. They come in these very ornate boxes, in which the individual portions are in their own boxes and wrappers as well.