If you're in to using old DOS games/apps - eg: retro stuff... Dosbox is a good one to install
I use SWEET HOME 3D in replacement of SKETCH-UP
Great resource bitsnpcs. Here is another Linux alternative to Microsoft you might be interested in adding to your list.
Creately -
http://creately.com/
Creately is also a graphic editor for Linux that is a great alternative to Microsoft Visio. Creately has everything you need for graphic editing with an extensive shape library, image search and a wide selection of diagram models.
PDF Studio
https://www.qoppa.com/pdfstudio/
Fantastic scanning / PDF program for linux.
Full suite like Adobe Acrobat (not the reader).
There really is no competition to it just yet.