We always stay at the Ko olina Beach Villas in Ko olina. Love it there! However, we are not a fan of the food/restaurants in Ko olina or nearby Kapolei. Which is why a rental car is a must for our family to seek out good, local dives and restaurants.
One of our fav places for local comfort food is The Alley at Aiea Bowl. The Alley is about 15 to 20 minutes away from Ko olina (assuming no bad traffic). They have a delicious Lemon Crunch Cake, oxtail soup (with or without ramen), kalbi plates, and other rice plates. Big portions and satisfying.
http://www.yelp.com/biz/the-alley-re...d-grill-aiea-2
Another fav of ours is this tiny onigiri/musubi place where you can order all kinds of rice balls with different fillings. Excellent spam musubi there. The Keeaumoku location is far more convenient than the hard to find Waikiki location.
http://www.tonsuke.com/eomusubiya.html
We always enjoy visiting the huge food court at Ala Moana Shopping Center - my fav is Yummy Korean BBQ, but there are lots of ethnically diverse food stalls.
Shirokiya (at Ala Moana Shopping Center) has a renovated, entire second floor dedicated to food. Lots of food stalls, bentos, etc. Huge selection.
One very popular restaurant is Side Street Inn. I am a fan of Anthony Bourdain, and went there after seeing him eat there on one of his shows years ago. I admit, that I was not wowed by this place at all. It is very popular though:
http://sidestreetinn.com/
Not far from Ko olina is Leonard's Jr. (Leonard's Jr. malasada truck) for fresh, hot malasadas. It is much closer to Ko olina than the original Leonard's Bakery. You can get fresh, hot malasadas at Leonard's Jr. It is in a parking lot near Home Depot, not far from Ko olina.
http://www.yelp.com/biz/leonard-jrs-...asadas-kaneohe
Zippy's, a chain restaurant, is in nearby Kapolei. Famous for their Zippy's chili and rice and other homestyle dishes. I like their Korean Fried Chicken plate.
Costco, Safeway and Target are not far from Ko olina and are in nearby Kapolei. Costco is great for stocking up on snacks, water, etc. There is also a big Walmart in Pearl City, about 15/20 minutes away from Ko olina.
Roy's is prob the better of the restaurants in Ko olina. However, we think it is overpriced for what you get. I would much prefer to venture out than eat there, but it is right there if you seek a nicer, close by restaurant for convenience.
I love Ko olina! Have a fantastic trip!