Just going to throw a few things that come to mind in terms of class options and powers:
Bard, swordmage, artificer: No desires whatsoever.
Warlock:
-New Pact: Celestial (standard and hex blade)
-Hexblades: Summer Fey version of fey pact, Star pact , vestige? (I think some of these may have been done in Class act on-line...?) Find ways for hexblades to benefit from standard warlock encounters [like they could take a warlock encounter instead of their weapon encounter].
-Binder: Rework the binder so it can piggy back off existing warlock spells while still being a controller. Fix some of the problems it had (like how their pact boon triggers when they kill [which is rare] or something next to the is killed [something they should avoid], make it key off something that a controller should be doing with their action) then make versions of it for the main warlock pacts. [OR just forget the binder and spend precious time and energy and pages on good versions of the warlock]
Sorcerer:
-New bloodlines/spells: shadow, aberration, Law (in opposition to the chaos sorcerer...)
-A written apology to the elementalist sorcerer. Not for him, to him. He was done a great wrong, Rules-as-written, and this is an important step to take before the healing can begin.
Wizard:
-Mage: mage class abilities for abjuration, divination, conjuration, transmutation, etc.
-Add abjuration, divination type spells (or the keyword to applicable existing spells), including at-wills and cantrips. I always wanted abjuration/divination at-will attacks (and encounter/daily I guess) because I think they could make for an interesting style of play.
-make fireball a spell people will use
-some method by which learing one spell gives you an at-will, encounter, and daily version in your spell book. Like if lightning bolt gave you a single target at-will, and multi-target encounter, and a daily that used the wall template. And have that count as learning one daily spell. I'm not sure if that's balanced, or balanceable, but I feel like lots of people would like having a thematic spell progression.
-classic/signature spells that scale with level, so you don't have to forget your favorite 3rd level encounter at level 17 or whatever it was, you can just do more damage, more aoe, better control, etc. [probably would be combined with the above idea]
Rituals: Yeah, figuring out rituals would be a good thing. They're just kinda tacked on and were either forgettable or problematically priced. They don't fit within the system as written with any sense of cohesion, and maybe that's just the way it needs to be, but it needs to be better at its job if it's going to be such an eyesore while doing it.