Its been a few years since Ive went, but I played on a few courses - I think the big thing is which area is your sister in versus if you plan on getting a car and getting around to different areas of the island.
Not far from Kaneohe/Kailua there is a course called Royal Hawaiian that I played. It had a cool rainforest type feel to it.
I'll put in Trip Advisor links in case you want to check them out:
http://www.tripadvisor.com/Attraction_Review-g60652-d3781005-Reviews-Royal_Hawaiian_Golf_Club-Kailua_Oahu_Hawaii.html
There is another one not far form there that is pretty popular called Ko'olau, but from my understanding it is a pretty difficult course. I may try it when I go back.
If you head to the North Shore area, there are two courses at the Turtle Bay Resort. I didnt play them, but I drove by them and they looked pretty nice. I think they get good reviews.
If you head towards the West side, there is a course I played called Ko'Olina. I think it was Michelle Wei's course growing up and an LPGA event may have been played there. It wasnt far from resorts, and was an enjoyable round:
http://www.tripadvisor.com/Attraction_Review-g60982-d526144-Reviews-Ko_Olina_Golf_Club-Honolulu_Oahu_Hawaii.html
The last one I played was Oahu Country Club. Its private, but they were open to reciprocal rounds when I was there, so it was pretty cool. Great views of the Honolulu skyline from this course. It was an older course, but still very enjoyable:
http://www.oahucountryclub.com/Club/Scripts/Home/home.asp
Have a great trip - Hawaii is a beautiful place.