Is it worth paying for Premium Economy?

For flights over 10 hours, yes. The extra legroom and dedicated check-in lines are worth the 30-50% price jump for a long-haul flight.

Should I book a round-trip or two one-ways?

Always book as a round-trip. It is almost always cheaper and prevents complications with airline policies regarding entry requirements.

Booking Your First Flight to Japan

Book your flights 4 to 6 months in advance using Google Flights to track price trends. Aim for a landing time in the early afternoon at Haneda (HND) to minimize travel stress and avoid rush hour transit.

Set up price tracking. Open Google Flights, enter your departure city and your destination (HND is closer to Tokyo than NRT). Turn on the 'Track prices' toggle for your desired dates to get email alerts when fares drop.
Prioritize Haneda (HND) over Narita (NRT). Haneda is 20-30 minutes from downtown Tokyo, whereas Narita is 60-90 minutes away. You will save roughly $30-$50 on airport express train tickets by landing at HND.
Check the baggage policy. Budget airlines often advertise low fares that exclude checked bags. Ensure your ticket includes at least one 23kg checked bag, as you will likely want the extra space for souvenirs on the way back.
Book directly with the airline. Avoid third-party booking sites (OTAs). Booking directly through the airline's website makes it significantly easier to handle rebookings, seat selections, and customer support if a flight is canceled.

Is it worth paying for Premium Economy?: For flights over 10 hours, yes. The extra legroom and dedicated check-in lines are worth the 30-50% price jump for a long-haul flight.
Should I book a round-trip or two one-ways?: Always book as a round-trip. It is almost always cheaper and prevents complications with airline policies regarding entry requirements.