I'd like a way to work on lyric content or project notes within a project file so I don't need an external text document and can work on everything inside Sonar.
 
Also, Scratch Pads in Studio One was a brilliant idea but I think Cakewalk could take that to the next level. I like the idea of being able to play with ideas but not have them modify the actual song I'm working on.

Lyric window happens be already available. Didn't know it either until I accidentally hit wrong quick key. Try alt + shift + 1 or from the menu view -> lyrics.
 
How does the Scratch Pad feature work in Studio One?

Good to know, I'll give that a try in a bit.
 
I've not tried it but most people who have S1 3 say it's pretty decent

Sonar does have a "Project Info" page that works something like a text document where you can store project information and input notes as well.  There is also a Lyrics section (I don't know how well it works as I typically don't input the lyrics of my clients) in the views section.  See if those work..