Most people will tell you that a car is a virtual necessity for getting around Rochester. Although largely true, especially taking into account the suburbs, the adventurous can manage to see a lot of attractions on foot or bicycle, and the patient can take advantage of the municipal bus system to traverse the entire county.
Of course, in winter all bets are off. Driving becomes potentially hazardous, biking becomes impossible, and walking is very much hit-or-miss.
Rush hours in Rochester are approximately 7AM–8:30AM and 4:30PM–6PM on weekdays.
By car
Six major rental agencies have desks at the Greater Rochester International Airport: Avis, Budget, Enterprise, Hertz, National, and Thrifty. Most also have locations scattered throughout the city and surrounding towns, and they will usually come pick you up if you're coming in from, say, the Amtrak station. Contact your preferred agency for details and locations.
Those who balk at needing a car to get anywhere in the Rochester area can at least take heart that it is a very drivable city. A common local maxim is that the travel time between any two points in or around the city is twenty minutes. The expressway system was designed in the 50s, when Rochester's population was booming; this growth slowed to a stop soon afterward, leaving a network of high-capacity roads that rarely see congestion. You'll encounter some mild rush-hour slowdowns, especially on Interstates 390, 490, and 590, but visitors from more populous areas will scoff at what Rochesterians call "traffic".
Construction and severe winter weather can disrupt Rochester's normally placid roads, however. In winter, pay close attention to traffic advisories, and if they say "no unnecessary travel"—they mean it. Most of the time, though, drive slowly and carefully and you'll be fine. It takes locals a snowfall or two to remember this every November, so be extra-cautious early in the season.
Outside of downtown, any place you want to go will have its own parking lot of some sort. Downtown, you'll find a mix of dedicated lots, street parking, public lots, and parking garages. Most surface lots are $5/day or thereabouts, with higher prices near the Blue Cross Arena on game/concert nights. The garages are generally priced reasonably as well.
By taxi
You can hire a taxi, but you'll need to call ahead to have one pick you up unless you're at the airport or the Amtrak station. Prices are set by the city at $0.50 per 1/6 mile, plus $2.00 per additional passenger. $10.00 minimum to and from the airport. Local limousine companies can provide more luxurious transportation for a somewhat higher fee.
By bus
The area bus system is the Regional Transit Service RTS, run by the Rochester Genesee Regional Transportation Authority RGRTA (http://www.rgrta.org/). While the buses are clean, efficient, comfortable, and cheap, the service has often been criticized as inconvenient.
The bus routes are designed as a hub-spoke system, optimized for travelers headed to and from downtown. The hub is downtown, so travelers trying to get from one suburb to another often have to ride one bus all the way into the city, then another all the way back out. The system works great for getting to the center of downtown, but the typical rider will be faced with a walk or another bus ride to get the rest of the way to his or her destination.
If the bus routes are convenient for you, though, RTS service is hard to beat, especially when the roads get slushy in winter. Every RTS bus has a bicycle rack on front, which can provide some flexibility if you're willing to bike to a bus stop. Fares are $1.00 per ride, or $3.00 for an all-day pass. $14.00 gets you a 5-day pass and $56.00 allows you to ride freely for a full month. Discounted fares are available for children and seniors although you'll need a Medicare or RTS low-fare card for the senior discount. The $1.00 fare is valid for an hour so you can change buses without paying again - however, you won't normally be given a ticket unless you ask for one, so let the driver know you plan to change.
Bus schedules are available online (http://www.rgrta.org/Sche...) and throughout the city, especially at transit hubs and information centers.
By bike
Much of the advice above for pedestrians applies to bikers as well, although bikers won't be able to make use of the Skyway. The Genesee Riverway Trail is fully accessible for bicycles, and they're a common sight all over the area in the summer, especially on the Erie Canal towpath. The low traffic in Rochester is a boon for cyclists, allowing brave ones to take to the highways but stay off the expressways!. Also, as noted above, all RTS buses have bike racks mounted on the front, which can be a great convenience.
On foot
Downtown Rochester is very walkable, at least for eight months out of the year. Traffic is light outside of rush hours, and crosswalks are plentiful. The Rochester Skyway is a system of enclosed elevated walkways and underground tunnels that connect numerous buildings downtown, including hotels, office buildings, and parking garages. It's especially useful in the winter, but the network only covers the east side of the river, and its continuity was severely disrupted by the recent closing of Midtown Plaza. Still, it provides a relatively warm, traffic-free route around the area. Look for the blue Skyway logo to find your way.
On the surface streets downtown, most areas are relatively safe, but be careful in the northeastern area bounded by E. Main Street, East Avenue, the Inner Loop, and N. Clinton Avenue, especially at night.
Outside of downtown, there are a number of pedestrian-friendly neighborhoods, including Park Avenue and the South Wedge, but they are not well connected to each other, or to downtown. Safety and navigation become issues the farther out you get from tourist attractions and recreation areas. Especially at night, you'll want vehicular transportation available.
One exception to the general lack of walkability is the Genesee Riverway Trail (http://www.cityofrocheste...), an almost-completed walking and biking route along the river. Once completed, this trail will take you from the Erie Canal on the south edge of the city all the way to Lake Ontario at the harbor. It also connects with other trails, especially the Genesee Valley Greenway south of the city.
Outside of the city, the inner suburbs are similarly hard to walk in, but there are pockets of village-like atmospheres where walking can be pleasant, such as Twelve Corners in Brighton and the Titus-Hudson area of Irondequoit.
By ship
Most boating in Rochester is exclusively recreational in nature, but you may find it a convenient way to travel between destinations.
The Genesee River is not navigable through downtown; you can go downstream from the south Erie Canal as far as the Court Street Dam, or upstream from the north Lake Ontario as far as the Lower Falls, but the three waterfalls and the downtown area are no-go. That still leaves some options, however. Mooring is available at the harbor near Lake Ontario and at Brooks Landing and Corn Hill Landing between the canal and downtown. The Erie Canal (http://www.nyscanals.gov) passes along the southern city limts, providing access from points east and west to the upper river. It's doable, but be sure to plan for the additional transportation you'll need once your boat is docked.
Note that the Erie Canal is drained every November and not refilled until the end of April.