A Realistic 2-Day Hakone Itinerary, With an Onsen Night in the Middle
Two days is the right length for Hakone. One day forces you to run the loop without stopping and skips the reason most people come, which is a night in hot water. Three days is comfortable but starts to duplicate. The plan below assumes a start from Tokyo, a night in the region, and a return in the late afternoon of the second day.
The key structural decision is which way round the loop you go. Almost everyone arrives at Hakone-Yumoto mid-morning and travels clockwise, so the ropeway and the boats develop their worst queues in the early afternoon precisely where the crowd reaches them. This itinerary follows the conventional clockwise direction on day one because it sequences the sights better, but it starts early enough to stay ahead of the wave. If you cannot leave Tokyo early, reverse it: bus straight to the lake first, and come back over the ropeway.
The second structural decision is where to sleep. Staying up at Gora, Sengokuhara or near Lake Ashi puts you in position for a dawn look at Fuji on day two, which is the single highest-value hour of the trip. Staying down at Hakone-Yumoto is cheaper and better connected but leaves you an hour from the view.

Hakone in a Day from Tokyo: Lake Ashi Cruise, Owakudani Ropeway, Museum and Onsen
Bookable directly through AsiaByLocals, with a verified local operator.
From USD 840
About 11 hours door-to-door