From the Bay Area you will want to take Highway 80 heading East to Sacramento. From Sacramento take 80 West towards San Francisco. Take the UC Davis Exit to get to campus or Richards/Olive Drive to go downtown.
There is an Amtrak stop within walking distance of campus, which serves the California Zephyr, Capitol Corridor, and Coast Starlight routes. Tickets from the Bay Area cost approximately $30 one way. If you are flying into San Francisco Amtrak is the best way to get to Davis. From SFO take BART to Richmond. Exit BART and then take the stairs or elevator up to the Amtrak platform. The Richmond station is unstaffed so Amtrak tickets can be purchased on board the train for no additional fee.
Although UC Davis has its own (small) airport, it is really only possible to reach Davis by plane through commercial airports. The closest option is Sacramento International Airport (SMF), from which one can then take a shuttle or taxi to Davis. A cheaper alternative is to take Yolobus. For $2 the #42B bus will take you to downtown Davis. You can then either utilize Unitrans, the local bus service or take a taxi to your destination. The airport is approximately a 30 minute drive from Davis.
The Oakland (OAK) and San Francisco (SFO) airports are also options for people who wish to visit the Bay Area as well as Davis. If your trip itinerary does not include the Bay Area, however, then SMF is the best option for commercial air travel to Davis. Amtrak trains are available from Oakland and San Francisco.
The Davis Airporter is another option for people flying in commercially. While it provides service to your front door and is available at all hours of the day and night, it is considerably more expensive than public transportation. See also the Yolo Airporter and the Super Shuttle.
Davis has the highest per capita number of bikes of any city in the U.S. It's the preferred method of transportation for most students and locals due to the prevalence of bike paths and the relative flatness of the area. Unitrans (the local municipal bus system) also runs quite frequently. For undergraduate students riding is free, for everybody else (including graduate students) one journey costs a dollar.
Downtown Davis is also very pedestrian friendly. The UC Davis campus and the heart of the downtown area run alongside one another and it's easy to stroll through both in a couple of hours.
Probably the worst way to experience Davis is by car. The huge numbers of bikers and pedestrians make driving slow and tedious at many times throughout the day.
UC Davis California Raptor Center: An educational centre that rehabilitates injured and orphaned birds of prey found in the surrounding counties. Large displays are present at the facility that allow visitors to see many of the birds up close. 
The UC Davis Arboretum is a 100 acre tract of land running along the banks of the Old North Channel of Putah Creek, on the UC Davis Campus. The arboretum is home to plant species that range from Mediterranean to South African and even includes somewhat smaller examples of California's North Coast Redwoods. It is the main source of horticultural information for inland California. The arboretum is a popular place for Davis students for walk, jog, bike, study, or just relax in the sun.
Davis has lots and lots of public art all over town. It is difficult to go anywhere or do anything without encountering sculptures, mosaics, paintings, or stenciled designs. An art enthusiast could be kept busy for days.
Check out the Toad Tunnel, a nationally infamous example of civil engineering gone horribly wrong. Located in southeast Davis near the Post Office and the Sudwerk brewery, the Toad Tunnel was designed to assist the local population of toads cross an I-80 overpass. Arguably, it has caused more problems for the toads than it solved. If you have any friends pursuing degrees in town planning, ask them about Davis' Toad Tunnel.
Davis Wiki: for more information about what to do and see in Davis, including event listings and reviews of local restaurants. 
Davis Transmedia Art Walk, 521 First Street, ☎ 530-756-3938, . 10:00am-10:00pm. The free, self-guided Davis Transmedia Art walk is the first of its kind in the country.The Davis Transmedia Art Walk consists of 23 public murals, 16 sculptures and 15 galleries and museums in downtown Davis and on the University of California. Each public art piece are embedded with RFID computer chip with interactive features. Artists lead tour are available through appointment. free. edit
Become a student. Davis is currently ranked as the second most educated city in the United States according to CNN Money Magazine and it shows. The downtown area is very youthful and is peppered with bars, coffee shops, and restaurants that are popular among the college crowd. The city of Davis is very conducive to college and graduate school lifestyles.
Visit the Mondavi Center, located on campus. A wide variety of performances can be seen year round, ranging from music to theatre to puppetry.
Shop at the Farmers Market. Open twice a week on Saturdays and Wednesdays, the Davis Farmers Market takes place in Central Park and offers fresh, locally grown foods. Much of the produce is grown organically. From March through September, the Wednesday evening Farmers Market becomes the Picnic in the Park, offering several restaurant stands, live music, and various other events geared towards a wide variety of ages.
Take part in Picnic Day. If you want to experience the single largest student-run event in the United States, visit Davis in late April and revel in Picnic Day. The day consists of over 150 free events, most of which take part on campus, including dog races, food tastings, exotic animal shows, an infamous Battle of the Bands, an exciting fashion show displaying unique student work and much much more. As one might expect, a good amount of drinking takes place throughout the day and by late afternoon there tends to be intoxicated people everywhere, but the mood of the event is very positive and arrests are very few relative to the number of the 50,000+ attendees.
Experience the Whole Earth Festival. Whole Earth is an annual celebration of counterculture, art, politics, sustainability, and music, taking place over a three day period on Mother's Day Weekend. Tens of thousands of hippies, punks, and miscellaneous weirdos descend on Davis for this event, taking place on the UC Davis quad.
John Natsoulas Center for the Arts, ☎ 530-756-3938, . The John Natsoulas Center for the Arts is a four story art gallery and the largest gallery in Davis. Their goal is to make art accessible to the public. One of the major roles of the John Natsoulas Center for the Arts is to provide a place for cultural meetings, conferences, and public activities, which create a wonderful community dialogue through a variety of visual, literary and musical events.free. edit
California Ceramic for the Advancement of Ceramic Art, Throughout Davis, ☎ 530-756-3938, . CCACA is a three day ceramic arts conference. In an intimate setting, you can interact with top artists in a way not possible at other venues. Enjoy delightful downtown Davis and be inspired by nationally recognized ceramic art talents. Demonstrations, lectures, and over 40 student exhibitions, no other event delivers more inspired knowledge of ceramic sculpture for a better price.Exhibitions are free and open to the public but the conference discussions and demonstrations are for a small fee. Held annually in the last weekend of April edit
Jazz and Beat Conference, 521 First Street, ☎ 530-756-3938, . This free two day event celebrates the music, poetry and art of the Beat Era. This event is held annually in October. The Davis Jazz Festival offers a wealth of sparkling musical gems and a selection of exciting performance painters for families and fans of all ages. Whether you’re looking for the haunting tones of a jazz chanteuse, the sounds of cutting edge, or hard-driving big bands, or classical jazz combos-or just a great cultural experience, the Davis Jazz Festival will deliver it all. Mounted as a collaborative event providing interaction between musicians and visual artists, the festival will serve as an educational event for creative youth and will benefit the Davis High School Band Program.Free. edit
Dos Coyotes Border Cafe, The Marketplace, 1411 W. Covell Boulevard +1 530 753 0922, . A very popular and excellent cafe serving up delicious south-western style cuisine, with inventive specials like corn quesadillas and monstrous salads. Started here in Davis, it's now got several locations in the Sacramento area. A second location in Davis at Oakshade Town Center, 2191 Cowell Blvd.
Chipotle, 227 E Street, 530-758-3599. Definitely the most mainstream Mexican joint in town, specializing in white rice burritos and soft tacos.
Stone Soup Catering & To Go, 423B L St, Davis, CA 95616 (530) 758-1719, . A local catering company serving Davis and Sacramento area, they also offer pre-order take out on select days listed on their website http://www.stonesoupdavis.com/.
Stone Villa Hotel, 4100 Chiles Rd (Davis, California 95616), ☎ 530-792-0800, . Located near UC Davis, Old Sacramento and the Mondavi Center for the Performing Arts. Complimentary breakfast and WiFI, outdoor swimming pool and meeting rooms.edit