EssentialPIM

i would do this:
the needed standard or customized layout is discribed in two further paragraphs!
I pretty much need to put a 2nd tasklist on left side, as you first write your tasks, like in clever pocket calendars, and then spread it into your calendar on the right hand.

epimtoday:
left sidebar only icons
one task list left, one right of appointments AND dependencies tasks on top of apointment area inbetween the tasklists. it builds a brigde or n over the appointments area in the middle. i quite sure add one more tasklist on the right, as one for now working on and/or important/need to do tasks, and one for the rest of the tasks. the month view would need to be exact the same. this two views are the most used.

epim month calendar:
left sidebar only icons
one task list left, one right of month calendar AND possibly also dependencies tasks on top of apointment area inbetween the tasklists.

the other most needed features are:
:floating appointments
:digital desktop clock as control center
:more to add icons/buttons in 2nd top menubar, like ...
-->it means you can add the module icons from left sidebar, calendar views, etc...
:extra window in one epim, like notes window.