Almost every city I build includes extensive infrastructure for bikes. It's hard to overstate how much this is a win-win for reducing traffic, improving accessibility of jobs and services, boosting public health, and keeping your city a nice place to live. The standout feature here is independent bike roads and shared roads with bike lanes, as well as a policy that lets you encourage biking across your entire city or in select districts. Skylines' first major expansion is also maybe the best overall.
