It really is a wide range, and knowing where you'll average will help. Off the top of my head I know that the following do well in the 20 - 35 ppt range.
Caulerpa prolifera, Acetabularia, Chaetomorpha aerea, Ulva, and a species of Gracilaria which I havent been able to ID along with a few other reds.
Java fern would be a candidate for the very low end of salinity. I'd say no higher than 5ppt, or at least that's as high as I could go with it.
>Sarah