Because of long distances from place to place, taxicabs are not the best way to get around Dallas. Also, it is difficult to simply flag one; you will probably have to call for a cab. Cabstands can be found at some big hotels and the airport terminals. There are about twenty cab companies including Checker, Dallas Taxi and Dallas Yellow Cab. It costs more than $30 to go from DFW airport into Dallas ($38 flat to the business district.) In general, cab rates set by the city are $2.00 initial drop and $ .40 each additional 1/4 mile with a $2.00 extra passengers charge. That can add up quickly when distances might span 30 miles or so. The going rate for tipping is 15 to 20%.
To really be able to see Big D, a rental car is a necessity. While there is large concentration of museums, historic sites and attractions and nightclub districts in the downtown area, there are many others flung far and wide across the city. Driving is a part of the Dallas lifestyle. In fact, Dallasites love their cars and you may marvel at how many new makes and models as well as well-cared for vintage makes and models you see on the roads. Going for a run often includes the attached irony of driving to a location like White Rock Lake to do it. Parking often seems to be the first consideration in development and while you might have to park a half a mile from your destination in its parking lot, you will probably always be able to easily find free parking. The exceptions are in the downtown area particularly around Deep Ellum and the West End nightspots and Lower Greenville Ave. as well. You will still find parking in those places as well; you will just have to pay for it.
All the national car rental brands like Avis, Hertz, Enterprise, Alamo, Budget-Rent-a-Car, and E-Z Rent-A-Car are available. There are usually plenty of cars available to rent, but book ahead around major holidays. It is easier to pick-up/drop-off at DFW, but cheaper to rent in the suburbs.
At the DFW Car Rental Center, which houses ten companies, there are Rental Car shuttles available to take you to and from your terminal departing every five minutes and it is laid out much like an airline terminal itself. Look for deals online, but be aware of the airport fees which add to the cost.
If you don’t need the rental car for the entire time, you are staying in a suburb or you are not arriving or departing from the airport, it is less expensive to rent cars from suburban rental car offices. Look online for good deals. Most rentals are flat rate, not by the mile. You will have to fill up with gas if you've seen much at all so also be aware of current gas prices when budgeting.
Because of its car-centric nature, Dallas is a city with a fair amount of car theft. Make sure your rental is covered by your insurance or buy the extra coverage. Break-ins are also relatively common so you are well-advised to keep possessions out of sight and park in well-lit areas at night particularly around the nightclub districts and in downtown areas. Other than heeding those precautions, "head out on the highway, looking for adventure."
Dallas' freeway and tollway system is well designed and easily navigable. Because the city encompasses 385 square miles a map is another necessity. Gas stations are everywhere and malls, shopping centers and large shops and restaurants preside. Traffic snarls are common, particularly during rush hours. If you get frustrated by one, pull over into the next parking lot and take a shopping, coffee, food or Happy Hour break. After a while you can mosey on.