I did not know about the evening checkin. Thanks for pointing that out but it seems like our airline does not provide that option.
We are staying in ZRH for a couple of nights. Would you recommend staying in central Zurich the first night and moving to Radisson Blu for the night prior to flying out? Is there a great advantage?

Our concern with staying in central Zurich is that trains dont seem to start until 5am, which in turn means we wont get to the airport until about 5:30. Is that sufficient time (1.5hrs) to check-in, go through security and get to our gate with an infant in hand?

-Rhainda