MySQLWorkbench is nice, but crashes a lot and isn't very customizable (for example, there's no way to do light-font-on-dark-screen). Sequel Pro is nicer in that regard, but it doesn't support multi-tab within the same connection and further "doesn't regard itself as a query editor." There's no save-as selection on the menu. If you use the keyboard shortcut, it'll try to save over whatever you last saved, regardless of tab.

I'm happy to pay for something good, especially if it's cross-platform; is there something good that people use?