Tom, here is what the OP said:
>>>Are we missing any other areas that may be closer for a day trip to the beach, or a day in Newport Beach? ........ We had a few extra days to use and wanted to be by the beach in OC. Any suggestions, recommendations about other areas, or nicer places in Cost Mesa if this is a best choice?<<<
So Anaheim, Garden Grove and Buena Park are not good places to stay for being closer to the beach or a day in Newport Beach. They can stay at a 4 star hotel, the Fairmont for well under $300.
The other thing they said was:
>>>We are trying to stretch the budget and NOT pay $300/night to stay right on the beach although the resorts look great<<<
They DON'T have a budget of $300 a night. They DON'T want pay $300, they are trying to stretch the budget, meaning stay in the best place with the biggest bang for the buck that is the CLOSEST to Newport Beach to make going to the beach easier and more convenient.
Staying in Anaheim you can walk around a lot of tacky motels and mediocre chain restaurants. I wouldn't exactly call that a bonus and Buena Park is even worse.
If I was looking to stay some place nice near Newport Beach it would NOT be Anaheim.
I don't run a tour company in Newport or Anaheim, I don't have a dog in that fight. I try to answer the question for the OP based on how they ask it and in the absence of other information.
I would choose any of the hotels in Irvine or Newport that I mentioned over any hotel in Costa Mesa, except the South Coast Plaza Hotel, which is a very nice property.