LoneRebel
Emperor
Ehh. Coastal cities aren't as good as some people here are saying. As Wodan pointed out, base coast or ocean tiles aren't very valuable. This ain't Civ III where naked coast or ocean tiles were pretty good if the city had a harbor, commercial dock and offshore platform. In Civ V, sea resources are pretty much the only sea tiles worth working.
I can think of only three other reasons to have coastal cities - to build ships, to build coastal wonders, and sea trade routes. These are all good reasons, with the last one being the most important. But if you already have, or can have, another coastal city or cities capable of building wonders and ships and running trade routes, then this city does not need to be coastal. Much of the time you'll only need one coastal city to run all your trade routes from, anyway.
I can think of only three other reasons to have coastal cities - to build ships, to build coastal wonders, and sea trade routes. These are all good reasons, with the last one being the most important. But if you already have, or can have, another coastal city or cities capable of building wonders and ships and running trade routes, then this city does not need to be coastal. Much of the time you'll only need one coastal city to run all your trade routes from, anyway.