Is there any plan for interior designs? I.e. underground caves (which i have seen mentioned), interior designs like castles and/or dungeons? Just wondering, so far a huge fan of this tool i have used it for several of my D&D outdoor maps

well I can suggest a hobby that starts off free for that but you soon get sucked in and buy lots of stuff,  

sell your soul and let your family starve

DAZ studio and DAZ 3D content (evil laugh)