Some things just are naturally easy in 3D and others are nightmarishly hard. Some things also look like they ought to be hard but are actually easy and also theres those that you think should be easy but aren't also. I have probably covered every situation therebut seriously, I think the key is knowing what stuff falls into which of those four categories.
I think that the contour lines to height map looks harder than it actually is - and I do have so extra tools to deal with all that stuff which I know very well.
The basics of the inn was mostly in the 'not too hard in 3D' category but when it comes to the beds, baths, "couple of Wargs by the fire...." type stuff then its moving into the 'known to be hard in 3D' land.
A generalized rule can be thought of which is how many steps would it take to make it in real life.
For example, making the balustrade was comparatively easy as each post is cloned and a simple lathe job. Some quick curve for the posts, lathe and multiply and its done. Anything squarish that you can do with a few boolean ops like add a block, subtract a cylinder etc thats all easy too. Posts, rooms, doors etc pretty easy stuff. Doing the barman, people, anything organic in general is hard.
If you have any specifics I can tutorial them but I probably wouldn't say anything clever or special.
In this inn example there are two distinct sections. There is the modeling of the objects and then secondly there is scene layout :- placement, texturing, camera, lighting and stuff like that. Those are two entirely unrelated skill sets. I don't do (character / story) animation but I expect that it would be a whole new third set on top of that too.
You can tell where I switched because as Ravs so nicely pointed out, it looked like Boogie Nights was going to break out from the wild color. You start with getting the objects right first and then go on to texture and layout. Seeing the objects with distinct colors makes it easier to tell whether the objects and their surface types are right.
S'pose its like anything tho - just put some hours into using it and you'll get it.