If you use the word "scale", then to me it implies a scale number, like 1/4 or 1/3, not just a wingspan. A 100" wingspan sounds big (and it is), but on "scale" it's relative. A 100" Cessna model is about 1/4 scale, which I would definitely call "giant scale", but a 100" B-36 is only 1/27th scale - not exactly "giant" to me.
SO yeah, depends on a LOT of factors. I'd consider a 1/12 Gotha G.IV as giant scale. 77.75" span biplane It's not the overly impressive "huge" builds you'd expect but it's a complicated build and is a project to assemble/disassemble for transport.
I'm of the opinion that the "catch all" rules of yesteryear are bunk but I get that for safety reasons there are needs to have guidelines. With a wider diversity of construction materials you really cannot classify everything the same, like Ben's C-47.
If it's too big for my home field then it's just too big... says the guy with an upcoming build WAY too big for his home field.