We usually recommend the Hugger Roller Bag 60L for trips up to 14 days (two weeks) and the 90L for longer trips. It also depends on what you pack - winter gear usually tends to take up more space, meaning 90L could be useful when going on trips with plenty of gear.
Sometimes airlines demand to mark the Hugger Roller Bag 90L as "oversized baggage" with extra cost, due to its size. We would recommend checking the approved check-in luggage sizes with your airline.