Pono Kai Resort in Kapa'a provides a central location for adventures throughout the eastern half of the island. We enjoyed the ability to walk along the beachside trail to reach the restaurants and bars in historic Kapa'a Town. We also rented a vehicle, and traveled as far as Koloa (south-central) and the Kalalau Trailhead (north) by car with relative ease. There was a small beach near the resort, but we opted to drive 10 minutes north to Kealia Beach instead.
The facilities at Pono Kai are great. We cooked breakfast in our room's kitchen on several occasions to take a break from eating out every meal. We honestly didn't spend a lot of time in the room, other than to sleep or pack/plan for the next day's adventure. Our room in building E did have a small view of the ocean, which was an added bonus since the room was advertised as a "garden view".
On the downside, the walls and floorboards are a bit on the thin side. We could regularly hear our neighbors talking and walking around in their unit, and we always heard them leaving early in the morning. We also had a woman staying in the unit below us knock on our door a midnight because we were apparently walking around too much. If you can get past this, then Pono Kai will work well for you. Also - Kapa'a doesn't really have a nightlife, but if you spend all day exploring, then you are ready to pass out at 10pm, anyway. The resort functions primarily as a timeshare, so don't expect to be greeted in person by your host, though the resort staff was friendly.