I'll usually keep to OBJ, 3DS, DAE and even SKP files until the very end. That way I can keep the mesh intact as much as possible.
I've found, especially with Sketchup, if I create an STL early on, it will usually make a mess of the mesh, so now I mostly import/export DAE files.
I'd love to know more about Blender as it's very powerful software and great for 3D printing.
The online bureau MakePrintable has been the life saver for me as I now use them for all the final translations to STL.
I used to use NetFAbb religiously in the past to create STL files, but still got, albeit minor, issues with the mesh here or there.
Example of STL import to Sketchup:

Example of DAE (or OBJ) import to Sketchup:

Cheers
NimROD