A question of scale

So, I finally sat down in earnest and started working on my Yeomanry campaign. First off, I poked around with Return to the Keep and In Search of the Unknown a little. I have decided that the connecting tunnel mentioned between the Caves of Chaos and Quasqueton exists, but I have decided that it runs through lots of natural caverns, which housed other bugaboos, who have prevented said tunnel from being used very much. I'm also going to use these caverns to explain just what happened to the two heroes from B1.

I've also been doing some wilderness mapping, but here's my hitch.... I'm using the Living Greyhawk metaorg map of the Yeomanry as my guide (minus the location of Slerotin's tunnel and Dark Gate... these don't exist). Each of the hexes on this map is said to equal 30 miles. I started mapping by drawing a gigantic blown-up approximation of the starting hex (where I am placing the Keep, the Caves, Quasqueton and a small starting town), but I'm having trouble with my scale. I'm using a numbered hex map to represent the larger hex, but I can't wrap my head around the scale. Is 1 hex = 30 miles mean 30 SQUARE miles? Or that each hex is 30 miles North to South in distance? Right now, I have it so that, if I assume that each large hex is 30 miles N-S, then my smaller hexes are each about 1.25 miles. I went with that, but then I kind realized... I think this is WAY wrong, because it makes that hex HUGE. BUT, if I consider 1 hex = 30 SQUARE miles... then that doesn't leave a hell of alot of room in each hex for extras.

My original plan was to map out about 8 of the larger hexes in detail, and use that as a "sandbox" for my game. But now, I'm not so sure. Anyone got any advice?

(Cross-posted to the CANONFIRE site, for help from the 'Hawkers. 8)