After mucking about looking for decent "Eldar-ish" scenic bases, i've settled on Scibors offering and purchased enough of the following to cover all HQ models being sent down to Vincent.
I bought one each of the 60mm offerings, however i'm not sure which one would suit the best (regarding the Avatar and Wraithseer). Both have to be mounted on 60mm bases, although I did have some image of the Wraithseer posed with a hand on the spire in the first large base image (with the pointy column). As if peering around the side, searching.
Personally, I think Scibor should do an oval sized base for the Wraithknights... I can really see them looking sensational on that scenery. Let me know what you think!