Have you tried putting in police stations, fire stations, hospitals ? Education also affects so you need educated sims, make sure you have elementary schools and high schools as well as a city college or a university and all are funded to requirements, make sure that commute time between residential zones and commercial zones is minimized, you can do that by adding mass transit or placing the zones closer, which would be easier. These are the factors that usually affect the desirability. Also make sure you have enough sims that want jobs before zoning too much commercial which wont grow! Focus mainly on every single point as well as the points you mentioned, put the airport far from the city centre though, because of noise pollution. Goodluck!