I like the idea of colonies floating about 50 km above the service, big floating cities. It turns out that an Earth-like atmosphere of nitrogen and oxygen at 1 atmosphere of pressure is a lifting gas on Venus, so basically your "colonies" become big baloons floating in the dense atmosphere. The temperature and pressure are surprisingly Earth-like at that altitude, but the atmosphere would not be breathable by humans and would be a bit acidic.

The floating colonies themselves would serve as a sort of sun-shade, especially if they were designed with low albedo to reflect some of the sun's light back into space. Combine that with other efforts to make Venus more human-friendly (atmospheric conversion, carbon sequestration, etc.) and you could terraform the planet. It would take a long, long time, but you could do it.