So even once bugs like this one (http://ludeon.com/forums/index.php?topic=803.0) are fixed, it'd still be nice to be able to go through and make sure your base has ceilings where you want them, without being forced to look for sunlight or rain.
Why not a simple "View Ceilings" button that would draw the roofs / rock ceilings wherever they are? Note that this shouldn't necessitate any sort of Z-level implementation. Ceilings already exist (and they're even drawn for a couple seconds when first constructed) so I'm proposing a simple toggle to be able to view them.
roofing is being redesigned.
If roofing is already being redesigned, then I'd like to suggest the ability to remove metal roofs (or require player confirmation before roofing new areas). It might already be in the works, but so far that's been a huge annoyance for me. I'm unable to place doors in some places where I'd really like them because it automatically roofs over my outdoor farming and solar operation.
Would be a nice change!
I think tynan is already planning on being able to roof yourself.