There are a lot of missions and campaigns on my mission site. Eventually we'll have a Campaigns screen where you can choose a campaign from a list and play it. (much like single missions at the moment)
Just been thinking some more about the Town Hall... Say we made the church use the town bell idea like you suggested, and made the Town Hall give you ability to buy upgrades instead, here are some ideas I had for upgrades:
Faster Building Construction (~20 Gold)
Laborer's build buildings faster.
Faster Road Building (~30 Gold)
Laborer's build roads faster.
Extra Goods (~50 Gold)
All buildings can hold one extra good.
Double Production (~100 Gold)
All buildings produce twice as many wares.
These are just ideas so take them with a pinch of salt, but I think with some tweaking it could be a really interesting building! Plus it still uses Gold, so it kind of fits the bill (you could still get the Town Hall after the Metallurgist).