Has anyone taken the train from the Zurich airport to the city station, Hauptbahnof? Would the tram be easier? Our day trips leave from the bus station across from the train. We are staying at the Radisson at the airport. Also, can you get your tickets when you get there or do you need to reserve them ahead? Any info would be appreciated.
Train is very frequent and much faster than the tram. Some trains are mainline trains to the ground level platforms and some are S-Bahns to the underground platforms. If you take a train to the underground platforms, take the escalator up one level to the passageway and go out the Sihlquai exit to the bus station.
Tickets are good on any train that day. You can buy at the ticket window, a ticket machine, or with an app on your phone. If you are returning same day, Buy a Day Ticket and it will include not only your return, but any public transport in Zurich for the day. A Day Ticket is exactly twice the price of a one-way ticket. A one-way ticket cost 7 CHF pp, so a Day Ticket will cost 14 CHF pp.
A ticket from the Airport to the City is valid both on the train and the tram, as the system is fully integrated. Trains are faster however. So just take the train. it is trivially easy. Trains are mass transit, you just buy a ticket and go.
But may I ask what day trip you are planning? You can easily travel by train from the airport to anywhere in the country, so booking a day trip is not needed to see the popular sights. In fact, a day trip adds complexity, and robs you of any flexibility. If you want to visit some place, just buy a return ticket from the airport to that place, and go on your own.