Thanks Jim.
For my part, if I use a function a fairly often (like adding a note), I'd want to get to it in as few clicks as possible. Which would suggest if other users feel that way, maybe having it immediately available in its own UI, versus having to click through a couple of steps to get to it.
Here's something that I've noticed some of the other 'players' in the ereader field do: the UI for adding a note doesn't even appear at all until you've selected some text. Then it'll appear in a little popup menu that will offer typical options: Highlight | Note | Share | etc. A few apps that I see doing some version this:
* Kindle for PC/Android, and Kindle e-ink
* Google Play cloud reader and android
* Logos Bible software
* FB reader on Android
* Adobe Digital Editions for PC
So, I would ask for: relatively immediate access to the note function, and some kind of popup menu on selection event (versus dedicated buttons in the UI), if that's possible to do without too much hassle.
ETA, attached an image from an Android app that does the contextual popup menu on selection.