I don't know about the plus sizes, but a few stores I went to are close to the city on Long Island. Beautiful Bride in Lynbrook, Bridal Center in Lynbrook, Lilette's in Bellmore and where I got mine...Elena Bridal in Merrick.
RK was a little much for me, my consultant was a mess and didn't listen to a word I said. I am sooo glad that you had a good experience.
Good luck, it's a pretty dress.