Well Crusader Kings forum has one, Stellaris forum has one, why not this? Especially since there are a bunch of user specific screenshot threads but no general one.
I'll start with an early to mid game symmetrical "main base" using only the domes available at the start of the game:
The micro domes serve as dedicated living space, while the small domes are the ones where the actual work gets done. Two farming domes, two research/factory domes and two general living space domes comprise the inner ring. Most of the water is still piped in from deposits rather than moisture farmed, but the original metal deposits around the area have already been mined out.
I'll start with an early to mid game symmetrical "main base" using only the domes available at the start of the game:

The micro domes serve as dedicated living space, while the small domes are the ones where the actual work gets done. Two farming domes, two research/factory domes and two general living space domes comprise the inner ring. Most of the water is still piped in from deposits rather than moisture farmed, but the original metal deposits around the area have already been mined out.