Night elf guilds do exist, but presently we are a little bit far and few in-between. As for classic age guilds with that theme, I cannot say I know of any. The world keeps changing and most seems to try to roll with those changes so to make interaction a little easier.
I saw some nice guilds on the forums that are popping up, and I really hope they take off. Other than that, we are looking to host a community wide few weeks of Kaldorei-aligned and open for all RP! Hopefully, this can bring some kindling to the community and Night elf/Kalimdor RP in general. You are super welcome to take part ^^ 