Discussion about the Costa Mesa Marriott and nearby alternatives has splintered into several threads. Here are a few others that have seen updates in the past 1-2 years:

http://www.flyertalk.com/forum/marri...ta-ana-ca.html
http://www.flyertalk.com/forum/marri...entral-oc.html
http://www.flyertalk.com/forum/marri...-marriott.html

At the risk of further fracturing the discussion () I agree with your assessment of the Costa Mesa Marriott. It's a comfortable if slightly worn hotel with friendly staff and a great location. It's my first choice near SNA. The rates can run high at times but occasionally I find a bargain.