I gave my books a closer look, to see if anything popped out.
Bard - helps in the multi-implement department and 3+ classes power selection
Eternal Seeker ED - helps even more with the power selection
Some of the Sustain powers also have Save Ends clauses, or similar things, that make them useless for this.
"Better Pinball" type powers are available, that include things that help out the pinballing, as part of the sustain.
Buff type powers, that normally would wear off, are usually stronger than Encounter length buff powers.
Of course, hopping across multiple classes with drive up the MAD; I'm sure some combos will be superior.
Most interesting, some of the Sustain + Effects are triggered by the round action of sustaining, (minor move or standard)
but you have the sustain automatically happening.
So when does the round action occur ??
Big question.
I'm thinking right now, and I might change my mind, that the sustain "action" happens at the start of the round.
This is a hole in the action process.
So then the effect/sustain extra stuff happens right off the bat, but who knows what kind of action it is.
As in No or Free or DM makes something up, or maybe Interrupt.
This might be worth it after all.
EDIT on 6-15-11
Improved Tome of Readiness discussion:
http://community.wizards.com/go/thread/view/75882/27781085/Wallizard?pg=1