Looking into improving my workflow and have a couple of questions:

How often do you use the Smart Tool?  Besides the Smart Tool, which other tool do you find yourself using the most?

I still feel a little overwhelmed having to toggle between clips and envelopes when editing tracks.  Any tips/shortcuts that make this easier?

Are there any workflow improvements in X2 that you are loving and can you describe how it makes like easier? 

I always use the smart tool. :) Never use anything else actually :)

The quickest way to toggle between clips and envelops is to left click on what ever you want active while holding the shift key

It depends. Under some circumstances I opt for a specific tool. However I use the Smart tool most of the time. 

The only tool I use regularly other than the smart tool is the mute tool. The rest is just about all smart tool.

1) Nearly always the smart tool.  Only exception that comes to mind is when I'm using the mute tool during comping/editing.
 
2) What Loptec said.

By far the greatest work flow improvement I was able to make was by using keyboard shortcuts.
I made a pdf document from the shorcuts as listed on the help and reference manual put it into 2 columns in landscape orientation, then printped it out duplex and laminated the 5 or so pages. it sits at my work station and is there for ready reference.

Are there any workflow improvements in X2 that you are loving and can you describe how it makes like easier?
 

I love auto zoom. I have it on in some of my screensets and off in others though. Having said that it's only Shift+Z to turn it on off.
 
Same goes for the Smart Snap. One small but often overlooked improvement is the dual snap settings. I have smart snap set as one and my preferred snap setting as the other which is view/use dependent. Combine that with screensets and that's a total of 20 different snap settings never more than two key presses away. You do need to set a variable IncludeSnapInScreenset=1 in the ini file though.
 
Being able to jump from one view all set up ready for the task in hand to another via screensets still takes first place for "greatest improvement since V8.5" though. IMHO of course.

FastBikerBoy

Are there any workflow improvements in X2 that you are loving and can you describe how it makes like easier?
 

...Being able to jump from one view all set up ready for the task in hand to another via screensets still takes first place...

Same here.  In each project I always set up several screensets and tend to switch between them constantly.  The attraction of screensets was my main motivation for upgrading.

you may also use the shortcut "T" which will pop-up the tool bar wherever your mouse cursor is.

+1 for mute tool.

I use F10 to switch to it when I want it rather than T+Click.

Primarily I use the smart tool.

The smart Snap work ok most of the time. Sometimes I find I have to go manually reset it because it doesn't seem to be working which is frustrating.