An often requested feature in GAFE related Communities on Google+ is the ability to merge cells in Google Docs. +Google Drive are you listening. Interestingly, you can merge cells in Drawings and Sheets but not Docs. Hopefully this means merging cells will be an upcoming feature in Docs real soon.
My first thought was, well since I can work up the table in Drawings or Sheets, and they support merging cells, I can copy and paste the table into Docs. Sadly, copying a table with merged cells from Drawings pasted in Docs un-merged.
My second thought was I could work up my table with merged cells in Drawings and then use +TechSmith SnagIt to capture the table as an image. I could then upload or insert that table (image) directly into Docs.
An advantage of this method is that you could use SnagIt's annotation features to highlight aspects of the table. The big disadvantage is that the data in the table is not live or editable.