I recently got back into it myself. My newest city is not as impressive, but I was urged to post mine so here is Brighton:
I have unlimited money turned on so I could relax and try to design a dense city that's efficient without having to worry about the budget. Right now I'm only at 20,000 people, but there's lots of room to expand. The body of water in the south is a river that expands into a bay, and north and east of the city is basically a big peninsula.
West of the highway is residential and east has commercial & office space in the north and residential neighbourhoods right by the water.
I initially started building this city as an experiment to see how well I could design a city using Bus Rapid Transit as the only form of public transit. But the BRT in the game isn't very efficient, so I quickly upgraded it to LRT. Then I added in some subways and the start of a commuter rail line.
The purple line is the LRT loop. It connects the residential parts of the city to commercial districts & office space.
The yellow subway line is an express cross-town subway line with only 5 stops that connects the main transit hub (airport, train station, and commuter rail station) to the University
The red subway line starts at the harbour and runs through the main commercial districts & office space (and has a stop in a residential district by the river as well)
The commuter rail line only has 2 stations - one by the airport, and one by the harbour, and you can see those (they are orange), but the line is harder to see because it is underground
Expansion of the city will happen east-ward, so that the transit hub is more central. I also want to expand across the river, so you can already see the start of the LRT expansion in the south-east
And yes, that highway exit has a roundabout above it, and one below it as well. I first built the one underground, and it doesn't work well for all the exits, but.. I'm not sure how to remove it. So if anyone knows how to remove underground tunnels with no exits, I would love to find out! I'd definitely leave this unique highway exit setup, but it would be nice to know how to do that for future screwups...