Gryffindor: hyped AF, hosting a frat party basically. Ready to get fucking wasted. Talks a big game about their new years resolutions but dont have any intention to actually follow through with them.
Ravenclaw: probably gonna sleep through the new years and just record the Ball drop. Will spend the day writing a list of their faults and ways to improve themselves. Will end the night with a bubble bath, a book, and a glass of wine (or martinelli's for the underage Ravenclaws)
Hufflepuff: will probably go to Gryffindor's party to be the responsible friend. They are the friend that makes sure no laws are broken. They like the company and seeing everyone being so happy and excited. They will probably bring extrafood that is New Years themed.
Slytherin: They dont really like New Years, they think its a stupid holiday. They also dont believe in New Years resolutions, they are already the best version of themselves. If anything they see New Years as an excuse to get drunk and throw some glitter around. They take a special joy in banging pots n pans together in the ears of a hung over Gryffindor the next morning.