Ann Arbor — The county seat, and home to the University of Michigan. It's a thriving town with lots of shops, restaurants, cultural activities and festivals.
Ypsilanti — Ann Arbor's smaller, poorer, uglier, and debatably cooler sibling. Ypsi residents tend to see their city as more relaxed and less yuppified; it's home to Iggy Pop and the Eastern Michigan University water tower, which was voted the most phallic building in the world by the nationally circulated Cabinet art and design magazine. The Depot Town area is the most walkable.
Chelsea — A quaint, touristy little town, home to Jeff Daniels' Purple Rose Theater and celebrated local restaurant The Common Grill. Has a small, lively downtown with several art galleries, eateries and shops.
Dexter — Small town between Ann Arbor and Chelsea with a walkable downtown. In the fall, visit the Dexter Cider Mill for fresh apple cider and doughnuts, and during nice times of the year stop in at the drive-in A&W outside of town.
Saline — Another pleasant small town with a walkable downtown full of shops and restaurants. Lots of people come for the Saline Celtic Festival that's held every July, with entertainment, food and vendors.
The other two villages in the county are Manchester and Milan (which doesn't rhyme with the Italian town, but moreso with "island"). Neither is very big, but both are worth a visit, especially if you enjoy drives through the country. Manchester has a little riverside downtown and an enormous annual chicken broil, while Milan has a carnival and lovely fireworks show over the water around the Fourth of July.
Northwestern Washtenaw County is home to the Waterloo State Recreation Area and the Pinckney State Recreation Area, both large parks with several popular recreational lakes, like Silver Lake and Bruin Lake.
Ann Arbor (and, to a lesser degree, Ypsilanti) is a university town, with a large number of international students. This means a lot of international restaurants, ethnic grocery stores, and lots of non-native speakers of English. There are several language schools in the heart of downtown, so as you're walking down the street, you're highly likely to encounter groups of people speaking Korean, Mandarin, Spanish, Arabic, or one of dozens of other languages. Of course, there are also native speakers from all over the country, and the rest of the English-speaking world, so you're liable to hear a wide variety of accents as well. For a small town, there's a surprising amount of cultural diversity.
Also recognize that you're not far from Dearborn, home to the largest Middle Eastern population in the United States. While the Arabic population of Ann Arbor isn't nearly as visible as its Asian (particularly Korean) population, you may have the opportunity to meet visitors from Arab countries or locals of Arab descent.
As for the native English speakers in the area, Michigan is situated in the middle of the Northern Cities vowel shift, which in some ways has made the local accents more similar to a Canadian accent. In particular, you're likely to notice a difference in the low front vowel æ (as in "hat" and "ramp"), which is raised and highly nasalized, and the mid back vowel o, which is fronted such that it resembles a Minnesota accent.
Ann Arbor and Ypsilanti are linked by the Ann Arbor Transit Authority (AATA), which provides routes all over Ann Arbor, between the Ann Arbor and Ypsilanti town centers, and limited routes within Ypsi. To reach any of the other towns and villages, you'll probably need a car.
Airport taxis and shuttle services between Ann Arbor and the Detroit airport are also available; details are on the Ann Arbor page.
The "most phallic" building in the world, apparently: the water tower in Ypsilanti, at the corner of Cross and Washtenaw, also locally called the "brick..." — well, you can figure that one out yourself.
The Chelsea Milling Company, manufacturers of nationally-beloved "Jiffy" Mix baking mixes since 1930, is located in Chelsea. You can call ahead to schedule a tour of their facilities.
Attend a movie, play, concert or comedy show at one of the many venues in Ann Arbor. Alternatively, actor Jeff Daniels has established a popular not-for-profit professional theatre, the Purple Rose, in his hometown of Chelsea.
The original Borders bookstore is in downtown Ann Arbor, a town known for its high bookstore-per-capita ratio.
Literally every town and village in the area has a quaint downtown area with pleasant dining and shopping. Ann Arbor's is by far the largest, but if you don't have time to meander through the entire county to see all the others, you should at least be sure to check out the historic Depot Town in Ypsilanti.
If you like to drive, there are some scenic paths along back roads in the county, particularly Huron River Drive between Ann Arbor and Dexter, which (unsurprisingly) follows the banks of the Huron River.
Go canoeing or kayaking on the Huron River in Ann Arbor.
The Saline Celtic Festival is held in Mid-July, with Highland athletics, bagpipes, music, dancing and food.
If you're an art lover, don't miss the Ann Arbor Art Fairs, also in mid-July.
Ann Arbor has a number of locally celebrated restaurants, and a wide variety of ethnic cuisines, but if you want to visit one of the most famous restaurants in the county, you'll want to check out the Common Grill in downtown Chelsea.
Saline, sister city to Brecon in mid-Wales and host of the annual Celtic Festival, is a good place to stop if you want a British pub experience or some local Michigan pasties.
Fresh apple cider is popular in the autumn, and most locals flock to the cider mill in Dexter between August and November to get their fix.
Being college towns, Ann Arbor and Ypsilanti have plenty of brewpubs and bars if you want to slake your thirst with something a bit punchier.
Despite the presence of Detroit to the east, crime rates in Washtenaw County remain relatively low, although violent crime is somewhat more common in Ypsilanti. In Ann Arbor and the smaller towns, at least, it's generally quite safe to walk through town even late at night. As always, though, be circumspect, and don't take unnecessary risks.
Washtenaw County tends to have a few cases of West Nile virus each year. If you're going to be out after dark, particularly in wooded areas, be sure to take mosquito-repellent precautions, like dousing yourself in bug spray and wearing clothes that cover your bare skin.
Ann Arbor has many historic homes which have been turned into unique bed and breakfasts..
To the east, Detroit is about 45 minutes away on I-94. Windsor, just across the Canada border, is about an hour. Be sure to bring your passport and photo ID to get into the country.
To the west, Jackson is about 40 minutes away on I-94, and state capitol Lansing is a little over an hour away on I-96.
To the north, Flint is about an hour away on I-23.
To the south, Toledo, Ohio is about an hour away on I-23.