Re: Kings Island 2014 Roller Coaster
A Wooden Giga could be possible, but it would have to be quite expensive. The appeal of the current largest woodies (Intamin Prefabs) is that they are built from pre-fabricated frames and track pieces, made out of glue laminated timber (gluam). Unlike traditional planks and wooden beams, gluam consists of several layers of wood glued together, making for some strong and light construction material (it's widely used in modern Norwegian architecture).
Prefabricated gluam elements can be made en masse and assembled into the truss support structures we know and love. The structure largely consists of identical pieces, with customized elements only near the track and possibly in the extra bracing. This drives the cost of the coaster down, giving you lots of height and length for your money.
However, as you go higher, trussing becomes inefficient on its own. You'd need some larger elements to provide reasonable stability and extra strength. Building a gluam support structure to hold up a 90 metre wooden coaster lift hill wouldn't be technically difficult, but you would have to custom make it for the coaster, and forego the traditional framework for larger beams. It would be a beautiful structure, no doubt, but it would become pretty expensive. Huge gluam beams and columns like those required would have to be provided externally, as I doubt the coaster manufacturers would have room or equipment to put them together in their own workshops. It would be a somewhat needless expense for little gain. Economically, they would be better off by going for steel for the lift hill, and that kinda defeats the purpose of a wooden coaster in the first place.
I wouldn't rule out the possibility of a Hybrid Giga, though. A lifthill not unlike I305 and trusses for the rest of the layout. But keep in mind that Gigas definitely cost very near the absolute maximum amount of money parks are willing to spend on coasters, so they would seek out the most efficient ways to build them. That one huge hill usually costs so much that the rest of the layout is kept as low as possible. The "ideal" layout for a woodie is several big air hils a la Colossus or El Toro, and that is only economically feasible in the size range of the aforementioned coasters.