1

Might be possible to take a Victory Liner bus from Manila bound for Tuguegarao, get off at Solano and take a jeepney to Banaue, but doubtful if you would make it in one day as you would leave Manila on a 1pm bus..
http://www.victoryliner.com/schedules/

2

You could take a Victory liner to Baguio then get a bus to Bontoc/Sagada early the next morning or continue on to Banaue

3

Unless you're really pressed for time, go to Baguio, then to Sagada, spend a little time there, then on to Banaue. You'll have to spend the night in Baguio. If you're making the trip north it's worth it to see both Banaue and Sagada. In Banaue you'll really want to get out to Batad, where the impressive terraces are.

Baguio to Banaue direct is a roundabout trip that takes almost as long as Manila to Banaue, not a great option. If you can get a Tuguegarao bus you might be able to reach Bagabag junction in time to get a connecting trip to Banaue, or you might end up spending a night in Solano.

4

Be warned. Baguio to Banaue and Manila to Banaue direct buses will be full of locals going home. Last working day before the holidays is on the 21st. I would say even those interconnecting buses will be full as well . Still doable but just be prepared with the hustle. Manila-Baguio won't be much of a problem.

Alternate on a day trip: Manila - Solano-Bagabag/anything toCagayan(Tuguegarao, Aparri)/anything to Isabella then get off at Bagabag, then jeep to Lagawe then another jeep to Banaue. Beware some jeepneys will lead you on and say they will go as far as Lagawe but will stop at Lamut. That will require another jeepney transfer to Lagawe.

On my last trip - I had to do this because everything was full (even that lone bus from Bontoc): Banaue-Bagabag-San Jose-Cabanatuan-Manila. This is the reverse route by the way.