The northernmost station in the BTS system, Mo Chit is number S8 on the Sukhumvit Line. It sits directly over one of Bangkok's busiest roads, Phahonyothin. While best known as a gateway to Chatuchak weekend market, Mo Chit is also useful if catching a bus from the northern bus terminal of the same name, heading to the Bangkok immigration office, Don Muang Airport or anywhere else in the city's northern reaches. One of Bangkok's largest parks is also located in the shadow of the station, and it's one of three places where the BTS connects to the MRT subway line.
Most travellers will only need to worry about one exit from inside Mo Chit BTS station -- number 1. Immediately at the bottom of the stairs, you'll see a line of taxis and minibuses awaiting passengers. Several minibuses (vans) found here can whisk you directly to Don Muang Airport and Bangkok immigration office for 25 to 40 baht. Minibuses headed to Kanchanaburi also depart from here every hour, though it may take some time and patience to find the right van. Taxis are also readily available -- a trip to Don Muang Airport or immigration will run 100-140 baht depending on traffic (make sure the driver uses the meter).
If you pull a U-turn at the bottom of the stairs out of exit 1, you'll see a large local bus stop right in front of you. Bus #52 can take you to the immigration office and #29 to Don Muang Airport. Both pass by every 20 minutes or so throughout the day and cost between eight and 15 baht. Exit 3 takes you straight down to another local bus stop, an extension of the one out of exit 1 really, where it's possible to hail any local bus or minibus as they pass. Note that most local buses and minibuses to the airport and immigration drop passengers off along the main roads, so if you take these expect a 10-minute walk, or to pay a motorbike taxi around 20 baht after being dropped off.
If you're heading in the other direction on Phahonyothin by local bus, take exit 4 out of the BTS station to reach a bus stop on the other side of the street. Apart from that, exits 2 and 4 access only a parking lot and office buildings with little else of interest.
Both exits 1 and 3 drop you at entrances to Chatuchak Park, which features grassy lawns, ponds and footbridges and is a fine place to go for a jog. Walk northwest all the way through Chatuchak Park and, after crossing over Kamphaeng Phet Soi 3, you'll enter Suan Rot Fai, a larger park that's also home to a children's museum (in the southeast corner), butterfly museum (to the east-centre of the park) and a Buddhist study and meditation centre (in the far northeastern corner). Immediately after entering Chatuchak Park, you'll also see one of the entrances to Chatuchak MRT station.
To reach Chatuchak market from the BTS station, take exit 1, walk straight south down Phahonyothin Road, take your first right (heading west with the park immediately to the right) and you'll see the east side of the market on the left. Note that Chatuchak market is a massive affair and its western gates can also be reached directly from Kamphaeng Phet MRT station, located one stop from Chatuchak MRT station. You'll also want Kamphaeng Phet station if heading to Talad Rot Fai.
Although Or Tor Kor gourmet food market isn't far from Mo Chit BTS station, it requires crossing not one but two daunting stretches of Phahonyothin Road, so you're better off taking the subway to Kamphaeng Phet, which has an exit that takes you straight into Or Tor Kor.
The other major point of interest for travellers in this vicinity is Mo Chit (northern) bus terminal. The largest bus station in all of Thailand, Mo Chit mainly services all northern and northeastern destinations but buses also run from here to to the east, west and even a handful to the south of Thailand.
You would think that Mo Chit bus terminal would be easily reached on foot from Mo Chit BTS station, but they're actually two kilometres apart. To reach the bus station on foot, it's necessary to go south all the way around Chatuchak Park and Suan Rot Fai (or through the maze of footpaths within the parks), then take a footbridge overpass to cross busy Kamphaeng Phet Road. Unless you have some time to kill (and a GPS), you'll probably want to hop in a taxi to reach the bus station, which shouldn't cost more than 50 baht. Alternately, local buses #136 and 145 pick up on the east side of Phahonyothin Road (exit 4 out of the BTS station) and make a stop near Mo Chit bus terminal.