I'd argue just about all SF races aren't alien at all [and that's not a problem at all]. How could they be? How could you write about something [or a compex system of somethings] that by definition has no connection, no common points of reference with human perception/experience/cognition? How coud you write about whats completely outside human conception while living inside human conceptual space?
When SF writers create the alien, all they're really doing its mixing up very human traits/elements/methods of organzing information/etc. in a new way. Instead of making a wholly new dish, they make a stew out of leftovers. Put another way, if all you have is wood to build a house out of, then no matter what oddball shape you build, you still end up with a wooden house.
So that leaves me asking: who uses the idea of the alien well? I think Solaris is a fascinating novel. A pretty compact argument about how we absolutely cannot understand the Other.