I never had the need for a griddle 
that size. A good while back I had 
a cast iron flat griddle about 12X24
that I would sometimes use on a 
gas grill when I had one, but it 
mostly got used on a Coleman-type
camp stove I had for hunting, fishing, 
and camping trips when we had a 
decent sized party along. 
Not exactly sure what happened to it, 
but I'm thinking that it went with 
some other stuff during a break in
when I lost a good bit of stuff. 
I have a smaller round stove top
sized one I've been using for a 
good while now. (12 inch?)
One of those made like an iron 
skillet with a handle, but no sides.
Can't remember where exactly, I 
stumbled onto a stack of them 
on a clearance rack for a bit 
over $3.00 apiece. I bought all
of em, and gave all but this one 
away to friends and family. 
Useful piece to have for the 
kitchen. I've made a gazillion 
sandwiches on it 
Not exactly sure what the cooking 
surface is on those big nice units 
whether it's steel or iron. 
Either way, the key is continual use.
The more you use it the better it will get 
Good Luck with it