I would do DLR from Bank on the way in, because...
1) The Jubilee is only slightly faster than the DLR. And as there's a
2 min journey from Bank to LB and the walk is slightly longer there,
there really won't be much in it.
2) There's often a scrum to get on the Jubilee Line in the mornings,
you can hardly ever get a seat, and there are quite often delays. The
DLR usually runs like clockwork in the mornings and, once you learn
where to stand, can nearly always get a seat.

And going home I'd do Jubilee to London bridge because...
1) The Jubilee is only slightly faster than the DLR. And as there's a
2 min journey from Bank to LB and the walk is slightly longer there,
there really won't be much in it.
2) The Jubilee usually runs quite well in the evenings and you can
generally get a seat. DLR likewise.
3) The Northern Line usually fills up at London Bridge so, if you get
on at Bank, you're unlikely to find a seat on that