Master of Orion has a fleet command point system. Each orbital base you have bring you some command points. Higher base tiers give you more points, but you can also upgrade a lower tier into a higher tier. If your fleet exceeds your command point total (either because you built more ships, or because you lost some bases) then your fleet maintenance costs increase dramatically.
A system like that could make fleet bases more useful, however it'd be one extra resource to juggle and that's not necessarily a good idea. It's just what all this talk about tying maintenance to star bases somehow made me think of it.