Domes are very strong and perhaps the best option for many areas. However, in rainy climates they are prone to leaks. (Domes originated in desert regions, after all.) In high rainfall areas, roofs with overhangs to protect walls are recommended. Roofs need to be very well built with hurricane tie downs. This is the weakest link in the design because roofs are vulnerable to wind damage, so study up on the specialized building techniques available.
Consider something like this Sand Castle house built by Steve Kemble and Carol Escott. Round, hexagonal or octagonal shapes are all good choices because wind will flow around the building. Same idea applies to the roof.
One big consideration is building on grade versus building on piers off the ground. Try to find some high ground and build on grade (or 1’-2’ above), since this will be stronger and less expensive.
Bag fill: The crushed coral/sand mix used on the Sand Castle is a good choice if available locally. Road base is more commonly available and can be stabilized with lime. Road base is the clay/gravel mixture used to build roads. It’s cheap, plentiful and very strong. And with lime added, walls become virtually waterproof and almost as hard as concrete.
One story structures reduce exposure. Design in fast mounting storm resistant window shutters. Keep roof overhangs to a minimum, maybe 24″, to help prevent uplift.
So in summary, a properly designed earthbag structure is the strongest sustainable building system that I know of. The only thing stronger is reinforced concrete, and that’s not sustainable.
I have numerous plans that could be adapted for hurricane and tornado prone regions at Earthbag House Plans.
These plans are available through Dream Green Homes. I modify plans at no extra cost to meet your codes.