Lived on the North Shore March and April last year. It was amazing. Great poke at the Waialua General Store, and every wednesday they would grill outside and I would get their steak plate for like $10. Paalaa Kai Mini-Mart and pick up some spicy shrimp rolls. I became addicted to them. They do not skimp on the shrimp and they are not dry like some you will find. Eat at Aiea Bowl. A bowling alley with great food. At least get a side of their Tasty Chicken. Their desserts are unreal too. The best garlic shrimp I had was at Ted's Bakery. Unfortunately did not find that out until right before we left. Also like their chicken katsu. Leonard's Bakery is highly hyped for their malasadas, and they live up to it. Their main bakery always has a line out the door, but they have some trucks around town that don't have the long wait. Go to the Haleiwa Joe's in Kaneohe and get the prime rib. But share it. It is huge. I had loco moco at 4 or 5 different places, but don't remember who had the best. The first was at Kaneohe Pancake House and I do remember it being way too much food and very good.
There are beautiful beaches everywhere. We would end up every late afternoon at Aweoweo Beach because is was about 5 minutes from our airbnb and was so peaceful with minimal people. On weekends we would go over to Kailua and Lanakai Beaches. I honestly like the beaches on Oahu better than Maui.