Replacing an established Leylandii hedge?

[Trailoftears]

Griselinia is a GREAT choice,a lovely granny smith rounded leaved hedging subject.A 2 ft  spaced single row is generous,or go a 3ft spaced double row.That gives you insurance,in that the outer line will take the 'hit' should you get a really proper salty or severe winter.These are known as 'New Zealand privets'hardy on the coast generally,but no guarantee of surviving say,-5 over 2 weeks of severe winter conditions.Yes,Olearia would work,and arguably 'tougher'-again,a N.Zealand 'shelter belt' plant-but see Griselina as Cinderella compared to the ugly sister!Go Griselinia for sure.I would say 5 ft is the minimum to keep Griselinia happy at-if thats your TOP acceptable height-increase your plant spacing-to be kind.

[Trailoftears]

As an afterthought-olearia will 'flower',but if you are familiar with the horror that is ragwort-you will get a hedge with a horrid white flower akin to ragwort.If you want a coastal flowering hedge with (generally)coastal hardiness-go escallonia Macrantha-quick growing too and 'proper' flowers.

[nepia]

If we're talking quick growing Kiwi stuff how about Pittosporum? Grown as large hedging over there and is salt tolerant as far as I know.

A bonus is the very strong and sweet nighttime scent from the tiny flowers that moths love