The Big Island's two coasts are so different that first-time visitors sometimes think they've arrived on different islands. Here's the honest breakdown.
The West Side gets roughly 10-20 inches of rain annually — sunny, dry, and consistently warm. This is where Hawaii's major resort hotels are concentrated: the Four Seasons Hualalai, the Mauna Kea Beach Hotel, the Hilton Waikoloa Village, and the Mauna Lani resort complex. The beaches along the Kohala Coast — Hapuna, Mauna Kea, ʻAnaehoʻomalu — are among the best in Hawaii. Kailua-Kona town has good food, coffee farms in the hills above, and the cultural history of the Hawaiian Kingdom's capital.
The Kona side is the better choice for: beach activity, resort amenities, reliable sunshine, and easy access to the Mauna Kea Observatory (the visitor center at 9,200 feet is an easy drive).
Hilo averages 130+ inches of rain annually and is the wettest city in the United States. That rain produces a landscape unlike anywhere else in Hawaii — lush, genuinely tropical, with waterfalls, botanical gardens, and a town center that hasn't been touched by resort development. The Hilo Hawaiian Hotel overlooks Hilo Bay with a view of Mauna Kea on clear days. The hotels in Hilo skew smaller and more affordable than the Kohala Coast resorts.
Hilo is also the gateway to Hawaiʻi Volcanoes National Park (45 minutes away) and to the Hāmākua Coast's waterfalls and Waipio Valley. The farmers market is the best on the island. The town feels genuinely local in a way that Kona's tourist strip doesn't.
If you're choosing one side: Kona for beach and resort experience, Hilo for genuine Big Island character and nature. If you have a week: split it — three nights in Kona/Kohala, two nights near Volcanoes National Park, two nights in Hilo. The drive across the island (through the saddle between Mauna Loa and Mauna Kea) takes about 90 minutes and is itself worth doing.