Any ideas in Thai for an equivalent of "for the sake of..."? I can easily build more specific phrases such as "for the security of" or "for the love of" but I can't quite find a good phrase for the more generic term "sake of" and have not been able to convey the subtleties to my wife to get a response.

What about เพื่อ?

This word carries the feeling a a sacrifice, just like "for the sake of".

เห็นแก่ or เพื่อเห็นแก่ are a bit stronger.

For example:

เขาตัดสินใจไม่หย่าเพื่อเห็นแก่ลูก

He decided not to divorce for the sake of the children.

In addition to what kriswillems said, there is also ...เพราะความ...

I did it for the sake of love.

ผมทำเพราะความรัก

Also works for safety.

But its closer to 'because of' versus 'for the sake of', so not sure if it gets your point across . . .