In my experience, the most important thing about a good parish website are the schedules! (and minimalism!)
The schedules: The time of every activity in the parish should be announced together on a single page with an explicit link to it from the main page. Since the most important things in a parish are: Sacraments and gatherings, knowing the exact time of these is the main reason people visit the page - and gives them a overview of the choices on the menu. Individual groups (like the choir or groups) could add a small text of self-introduction with a friendly invitation.
On minimalism: In today’s world there is such an abundance of content that the slightest content becomes burdening and time consuming. The parish web site is all about calling people into the parish.
On history: A comprehensive “history of the parish” is very nice since people enjoy knowing the history of their own parish.
Added bonuses: If the priest would like to sometimes select one of his favorite sermons for transcription the faithful would enjoy their friends production.
Broader perspective: If you are in an urban dioceses with many parishes close by, grouping some of the schedules of other parishes together adds for choice if for example you miss mass in on parish but can still make it in time for mass in the neighboring parish.