For the events centre, I would prefer an imposing streetfront presence rather than having a plaza in front of the building. This would accentuate the urbanity of the core (God it needs it!!)
Examples would be:
This would not preclude the inclusion of heritage elements in the facade, and in fact this would be a very nice touch which would certainly help to define the events centre with relation to other similar venues in the region. In particular, given it's location on the old ICR HQ site and ICR railway station, a railway theme of some kind would be ideal. Perhaps the facade could be crafted to resemble a grand old railway station...
This is the old ICR station that used to occupy this site before Highfield Square. The centre part of the station could certainly be used as an inspiration for the main entrance to the events centre.....
If we go for a railway themed building with a major street presence, I don't think this necessarily precludes glassed in concourses like
mmmatt showed us....
A concourse like this could be included on the
side of the building, perhaps facing the driveway leading into the property from Highfield Street.