What about something like this - an HTML generator for Table code?

HTML Table generator - TablesGenerator.com 

Rhia,

This looks good, but would not prevent the Nintex editor from changing the HTML after saving.

Also, the Nintex editor uses its own CSS wrappers for inline style settings, so we'd really need something that works with these settings rather than fighting against them (as I currently am). It would be great if we could switch them off...

Are you making your changes in the WYSIWYG editor or the code editor?

I've always found the code editor to be much more reliable than the WYSIWYG editor.

Yep - agreed - this is sort of the angle I'm taking as well. If you use the table generator and post that directly into the Code Editor, it should retain. As for CSS overriding it ..

https://blog.bonzaiengineering.com/tagged/css 

Here's a good blog post (by one of my colleagues, I am biased) that can teach you about the "not" selector. Maybe this is something that can be used to exclude tables, if your form is CSS heavy?

I generally build a table in simple HTML first, then add the labels, and list column contents in WYSIWYG format. The big problem with this editor is that the work put into formatting one email layout cannot be re-used - we cannot copy the HTML into a new email layout; it just won't work -we'd all ways need to re-add the columns and perhaps formatting.I would be happy even if we had the option of formatting in simple HTML, without CSS,

I'm looking, basically to format a 2 column table - left column with labels in black, data on the right in blue. Why is it so time consuming to do this in this Editor.

Not sure if this will help or not but I've been working on the same and found an easy (ish) way is to use variables and code them accordingly. One for subject details - mine can change based on the setting of the status, another for the styling (which includes the table css), another for the message body, another for a header table and one more for a table that contains a list of data from a sharepoint list.

I know it's not the best way but it works for me - at the moment.

I recently faced an issue, when I copied-paste a table into Nintex email body what made the email sent without a body at all! There were no contents in received email. I was really angry and just put a plain table, without any formatting instead, what solved the issue. Yeah, it would be really helpful to have simple table editor built-in to WYSWIG editor.

Regards,

Tomasz