I try to keep domes that are on the same general side of the Mega Dome positioned so that their connections are in the same wedge or group of wedges, but every dome is only directly connected to the residential dome. With the residential "hub" I might put parks, Smart Houses, or small services in the wedges used for connectors to avoid unused space, but other than that I try to avoid "losing" multiple wedges to connectors where possible. Even with the above setup, it's possible to create a residential hub capable of housing something like 5-600 people, far more than you could possibly need in most cases. Also, try to keep your farm dome and service dome close to each other if you follow this setup since it means drones can take food from the farms to either put into storage or transfer directly to diners and grocers.
One interesting thing to note is that if you connect three domes together so there's only one dome connected to both the others and those two are close together, colonists that live in the "hub" dome will actually travel along the surface outside the domes and connectors between them, which can save resources if you're willing to deal with a sanity hit early on. They will, however, only travel to or from the hub by connectors, it seems.
Granted, there are situations where you want smaller clusters, either for space or other reasons. For instance, if you plan to set up a mining center and don't have the required breakthrough to keep extractors running after the depost is depleted, you'd really only want a residential dome and maybe a farm/services dome since it can be more cost-efficient to just have the resources used in factories elsewhere. If you want to set aside a cluster for workshops, just build any sized dome, fill it with residences until you have the population size you want, build a few domes for workshops, and then fill any remaining space (after connections) with services, perhaps add a farm dome to keep it more or less self-sufficient.