If you can take a vehicle directly to your destination, or a short walk from it, things works pretty well. If you need to transfer, even once, you can easily double trip time (consider a typical commute is ~20 minutes one-way).
Scheduling transfers with shared-roadbed (e.g., bus, light rail) systems is all but impossible.
Prior to the creation of early transit systems (horse-drawn omnibuses, either wheeled or tracked), few cities had a cross-section of more than 1-2 miles, as 1 miles is about a 20 minute walk. Streetcars (horse, electric, steam) extended that based on their average speed, typically 5-15 mph, with a 5-10 mile commute becoming possible though still usually less, and those commutes forming along rail lines, hence a hub-and-spoke city layout (see for example Chicago). Dense grids such as New York's were unusual.
Personal (or small-ridership) vehicles can go directly point-to-point, and make longer, flexible-route commutes possible (I'm not saying this is a good thing, merely a fact), though requiring parking, chauffers/cabbies, automatic vehicle control, etc.). In an interesting parallel, one reason there were so many horses in late-19th-century America was because of railroads. You had 30-60 MPH transit along fixed routes, but limited movement within cities or towns. So horses, wagons, and coaches to get to and from railway stations for goods and people. Petrol-powered automobiles replaced horses before they substituted for trains, though railroad use was already in decline by 1920 (rising one last time due to fuel rationing in WWII).
Upshot: there's a place for public transit, but almost certainly only with massively revamped land-use within urban and suburban regions.
So grey-hound or car rentals are your best bet unless you already own a car.
