Thanks all, appreciate the feedback. I do recognize the Mavis takes up a lot of space, but it was the device that got me to take the jump to modular so just made sense to include it in my first rack. And to that end, this is just my first go and I actually ended up getting a lot more than I initially though I would. Based on my reading here, this won't be the end, so I'm sure at some point I will take it out and put other stuff in there.
On the utilities front, I would be curious for a few more specifics. I do have Maths, Pamela's Pro, the Zadar, Quadratt, the Belfaco Instrument Interface, the Intellijel MIDI CV and Expander (I have a Zaquencer that I can use to sequence up to four channels), the Happy Nerdings 4X mixer and lots of utility functions built into the other modules so I thought I was pretty well covered. Still, I am new to this and very much appreciate the learnings I've got from spending a lot of time (probably too much!) on this site and ModWiggler. So let me know.
Thanks.