I don't know if this suggestion has been posted or not, but my quick search yielded nothing - so here goes!
My little hatchie is just about ready to begin his Helian RoP, so I've been looking around for prospective Lairs to call my own - particularly in the cold north. I figure once I ascend I'll want a homestead to call my own and really become part of Istaria.
I was looking around at all these lairs - ranging from Brist to Mahagra and I noticed the dimensions vary greatly based on the topography of the land (temperate lands favor larger, cubic lairs and icy regions favor narrow, deep lairs). I found a lovely Lair just north of Blizzard's Reach - the view is magnificent, resources are close...but I'm unable to see how the space actually lays to see if it's good for building an efficient lair (in my eyes anyways).
Talking with my elders in the NPA and the Dragon channels - I also saw that construction was no less of a headache. Lairs, by design, are three dimensional - the current system in place doesn't appear to allow the player to view their construction blueprint in 3D, instead they work floor by floor and try to build around structures that descend anywhere from 2-4 floors and attempt to carefully match up doorways to make these rooms accessible and usable.
I personally think it would be easier, both for purchasing and construction reasons - if we were able to view the space in a three dimensional manner. Even if it were something like a pane to view top/left/right/bottom with appropriate gridding in which to view multiple levels would be wonderful. Being realistic and perhaps for an easier fix - I noticed that the (?) button did nothing when pressed in the plot survey screen - perhaps a tutorial addition could be made?
As I understand it those who've built their Lairs use anything from an online grid to leggos to assist in the planning process.