Yes,You can! But the good accommodations are always need to book in advance. The Tet festival is always less tourist, especially in Hanoi than before and after Tet festival period. Be careful of some "street boys" who always hold the hotel cards to show you at bus station or railways station. He bring you to the hotel to get commission. Don't miss arrange your food for 2days, most of the restaurants will close during Tet festival.