The great American road trip is on -- even with the high cost of gas. Traveling a few hours from home to see local sights is still affordable, and knows where you can drive without breaking the bank.

If you're looking for a day trip out to add on to a business or pleasure journey, though, Frommer's can suggest great destinations ideal for public transportation, where you won't get hit by the double whammy of high gas prices and daily car rental fees.

You can't assume fuel is "free" any more. But especially when you pack people into the car, or drive a fuel-efficient car, driving still compares favorably to the price of bus and train tickets. We've analyzed several trips from four major American cities, taken by three sample people:

  • Patty Prius, driving all alone in her fuel-efficient 2006 hybrid
  • The Camry Couple in their trusty 2006 Toyota
  • The Ford Family, two adults and three children in a 2006 Explorer SUV

We took local average gas prices from (

As you'll see below, taking to the road can still make sense if you have your own fuel-efficient car and your own place to park it at home. But if you plan to drive alone in a gas guzzler, or you balk at car-rental fees, it makes sense to hop on a train or a bus.

New York City's great public transit system makes driving a car an unnecessary hassle. Frommers' book, "Great Escapes from NYC Without Wheels," offers dozens of ways to get out of the city, including romantic weekends, spa escapes, food and wine adventures, and trips to historic country towns.

You can take a gamble on Atlantic City, but don't take a car. It just isn't worth it. New Jersey Transit offers frequent trips to Atlantic City from the Port Authority Bus Terminal in midtown Manhattan for $29.85 each way. If you intend to gamble, you can do even better with Academy Bus, who offset their $35 fare with $20 credit at various casinos.

Driving to Atlantic City, including gas and New York City bridge tolls, costs $27 round-trip for Patty Prius, $38 ($19/person) for the Camry Couple and $61 ($12.20/person) for the Ford Family. But remember the hassle of parking, especially in New York City.

Who knew there's art even beyond the boundaries of New York City? The denizens of Cold Spring and Beacon, NY do. These two towns on the scenic Hudson River are home to charming cafes, B&Bs, antique stores and a huge modern art museum, Dia:Beacon. Stop by the museum in Beacon first, then hop back on the train for a seven-minute ride to Cold Spring, where the eight-block downtown looks like a postcard of historic Americana. The two towns are easy to access as a day trip from New York, served by the frequent Metro-North Hudson Line at least hourly; round-trip off-peak adult tickets cost $34. Compare that to $10.16 round-trip for Patty Prius, $15.61 ($7.80/person) for the Camry Couple and $26.55 ($5.31/person) for the Ford Family.

Washington, D.C.'s Metro system makes bringing a car to the city an unnecessary expense. Never mind D.C.'s extremely confusing layout of diagonal avenues and one-way streets, which have driven many a visitor to distraction. The surrounding states of Maryland and Virginia offer plenty of top day trips and weekend getaways where a car is an option, not a necessity.

Baltimore, Maryland has always had a bit of an inferiority complex compared to its more powerful neighbor to the south, but Frommer's has been singing about the charms of Charm City for years. Affordable restaurants, quirky museums, and a terrific aquarium make Baltimore a great day trip for all ages, and you don't need a car to enjoy the attractions. In fact, riding the city's tourist-centric water taxi is a big part of the fun. To get from D.C. to Baltimore, your best bet is to take the MARC commuter train on weekdays for $14 round-trip, or Amtrak on weekends for $28. Round trip driving for Patty Prius costs $6.89 in gas; for the Camry Couple, it's $10.68 ($5.34/person) and for the Ford Family it's $18.16 ($3.63/person). But factor the cost of parking, the perpetual traffic, and the un-loveliness of the drive up I-95, and the train looks better and better.

For a weekend away from D.C., Colonial Williamsburg, Jamestown, and Yorktown offer three opportunities to steep yourself in history. Take some time to duck back into the 18th Century in restored Williamsburg and Jamestown. If you need to raise your pulse, pop over to the Busch Gardens water park for a few rides on the slides. You can do all of this without a car. Twice-daily Amtrak trains from D.C. drop you in Colonial Williamsburg for $70 round-trip per person, and there you can pick up public shuttle buses to Jamestown, Yorktown (both from March-October) and Busch Gardens (all year). Driving is even more affordable, provided you're not renting a car. Gas would cost $25.28 for Patty Prius; $38.27 ($19.14/person) for the Camry Couple and $65.08 ($13.01/person) for the Ford Family.

San Francisco is surrounded by charming towns and gorgeous countryside. While driving down the California coast is one of the greatest road trips in America, you can still tour towns and taste local wines by bus and train -- and you won't have to worry about having a designated driver.

Just a short way up the bay from San Francisco is the former hippie haven of Berkeley, still home to a beautiful college campus, extensive parks, world-class restaurants, and eclectic shopping. It's easy to get to Berkeley on BART subway trains, which run several times an hour for $6.80 roundtrip. Including tolls, it will cost Prius Patty $5.19 to drive to Berkeley, the Camry Couple $6.16 ($3.08/person), and the Explorer clan $7.70 ($1.54/person) -- but start to factor in parking, and you have a deal via rail.

Head south from San Francisco by car or transit and you've got a full weekend of activities in the Monterey area. Grab a hotel in Monterey and hit the aquarium, then take a Monterey-Salinas transit bus down to Big Sur or on the Carmel Valley Grapevine Express, which runs every hour and passes ten tasting rooms. An MST "Super Daypass" costs $9. To get to Monterey, you can pick up an MST express bus in San Jose three times daily. A full weekend costs as little as $33 per person via public transit, including CalTrain service from San Francisco to San Jose. Driving, that will cost $37.65 for Patty Prius, $56.85 ($28.42/person) for the Camry Couple and a shocking $96.67 ($19.33/person) in that gas guzzling Ford Explorer!

Dallas isn't known for its public transportation -- but maybe it should be. Recent improvements in the city's bus and trolley system means it's possible for visitors to enjoy the city without driving on the wide roads Texas is known for.

Our top day trip from Dallas, Fort Worth has a charmingly renovated downtown, world-class museums and the Stockyards Historic District, part Old West theme park and part living history museum. It's safe to say that if Dallas is Texas leaping forward into the 21st Century, Fort Worth still has a smiling eye on the 19th. It's only an hour between the two cities on the swift, efficient TRE train; a day pass costs $5/person. When you get to Fort Worth, "The T" Bus shuttles you between attractions. A round-trip for Patty Prius costs about $5; for the Camry Couple, around $8 ($4/person) and for the Ford Family around $14 ($2.80 /person).

If you want to extend your trip out of Dallas, getting from Fort Worth to Grapevine is half the fun. Frommer's recommends the Grapevine Steam Railroad, running a steam or diesel locomotive with vintage coaches from Fort Worth to the Old West town of Grapevine, once daily on Fri-Sun for $14. According to our experts, the railroad is one of Texas' top travel experiences. Within Grapevine, a local trolley helps you get around the town to tour the 75 historic buildings and the huge, nearby Grapevine Mills shopping mall. To get back from Grapevine (or get there without the train), take a $20 taxi to or from DFW airport and connect there to the TRE train.

Driving to and from Grapevine is relatively cheap and easy from Dallas, but you don't get to ride a vintage steam train that way. Gas costs $3.80 for Patty Prius, $6.03 ($3.01/person) for the Camry Couple or $10.27 ($2.05/person) for the Ford Family.