Alaska's cities - their charm lies in the character of their people

A guidebook to Juneau sums it up: ''For Mt. Roberts, you take the wooden stairway at the end of Sixth Street and continue upward.'' Mt. Roberts is a 3,800-foot peak. Past its summit, the Juneau ice field stretches unbroken and trackless for 1,500 square miles. But six blocks from the Sixth Street stairway, Le Petit Paris serves croissants and barquettes aux marrons as good as the best in New York.

Alaska blends wilderness with the most sophisticated modern technology. Part of the charm of the state is that the telephones and the post office work. It defies logic to pick up a telephone in the Pribilofs in the center of the Bering Sea (in a mid-size Alaskan town - St. Paul, pop. 591) and speak within seconds with Minneapolis. But this is the United States - and in Alaska's cities you know it.

Urban Alaska - embracing Juneau, Anchorage, Fairbanks - runs small. There are after all only 400,000 people in the whole state, 100,000 fewer than in Seattle and fewer even than the annual number of tourists. None of the three cites is a metropolis - not even Anchorage, which is by far the largest, with a full half of the state's population. And yet Juneau, the capital, with a population of only 21,000, is without question a cosmopolitan city.

Juneau looks like a small town. Old pastel wooden houses climb the hill from the Gastineau Channel - the demands of their precarious perches made clear by the long wooden stairways that continue almost every street up the mountain.

But within a dozen blocks stand: the State Capitol; one of Alaska's most comprehensive ethnographic museums; a nature-food restaurant - the Fiddlehead - that rivals anything in Boston; a playground in the side yard of the oldest extant Russian Orthodox church in Southeast Alaska; an active waterfront; formal Victorian houses that are still residential; and a business district that has everything from Haida bowls to a tiny obscure screw for a Swiss Army knife.

The streets are decorated with the umbrellas of sidewalk carts - one selling Vietnamese snacks; another, gourmet sandwiches; and others, hot dogs.

A few feet from the road along Gastineau Channel, a friend of mine backpacks her young daughter while she catches enough salmon to can for a winter's supply.

Five minutes on foot from the State Capitol, Basin Road curves into unbroken green across an old bridge with wide wooden planks, past a long thin waterfall, and follows a small stream - Gold Creek - toward a bowl of snow-streaked mountains.

It is to Gold Creek that Juneau owes its existence as a city. Juneau was the first big gold strike in Alaska - 1880. It was the first city to boom into existence since the Purchase, thirteen years earlier.

But the real charm of Alaska's cities lies in its people. Take Regina Charbonneau of Anchorage, owner of Regina's, a French restaurant with a menu flavored with creole that would be superb anywhere. Originally from Natchez, Miss., she went to an isolated site in the Aleutian chain to cook for a camp of construction workers, determined to earn enough money to go to Paris and study to be a chef. The camp was primitive - ''Of course I was wearing my correct little wool dress'' - but the workers brought her local delicacies, such as birds' eggs, which she adapted to French cooking. These she served by candlelight, insisting the workers dress for dinner.

When I met her last July, I saw a fine-boned woman in a designer dress, who looked as if she would be more at home in Paris, but she is clearly made of the stuff one finds in people over and over agian in Alaska - steel.

In Anchorage the contrasts of Juneau are magnified many times.Its setting is utterly improbable - to the east is Mt. McKinley and the Alaska Range; to the west, the snow, mountains, and glaciers of the Alaska Peninsula. The civic symphony actually predated paved roads. Now, however, the downtown streets are the starting point for the biggest dog sled race in the world, the Iditarod - 1, 000 miles over a legendary trail to Nome.

On a bright July day I rode into a spectacular untrammeled landscape only minutes from downtown Anchorage, on the Kenai Peninsula. On the left, blue mountains were reflected in the pools left by the receding tide in Turnagain Arm. Its name is a memento of the exploration of Alaska by Capt. James Cook in 1778. He had to turn and turn and turn again to get his ship out of the shallow inlet. Some of the strongest tides in the world occur here - up to 40 feet; and the mud flat is a mire - although a beautiful one of quicksand.

Portage Glacier, farther down the road, is evocative of a harsher past, and of the long-established cosmopolitan character of the site of Anchorage. The glacier actually was a portage, a trade route for Indians of the area. Anchorage has grown from those origins: with its establishment as headquarters of the Alaska railroad, with the development of farming in the Matanuska Valley 45 miles north of the city, with the construction of military bases - and with oil. Anchorage is still in trade.

In Anchorage, there are small frame houses, as there are in Juneau, perhaps with a tent in the backyard - but beside them tower glass-walled skyscrapers.

I came upon a young man playing a grand piano set on a flatbed truck on the main street of Anchorage. Jeeps and pickups, the utilitarian all-Alaskan vehicles, drove past as he played Beethoven and then his own jazz compositions.

Surprise and what would anywhere else be anomaly are the signal characteristics of urban Alaska.

Of the three cities, Fairbanks shows the rough edges the most. Like Anchorage, it had its origin in trade, but much more recently and accidentally.

It began as a trading post at a spot where Capt. E. T. Barnette was forced to disembark by low water from the steamer he was traveling up the Chena River to the chosen spot for his operation. Fairbanks prospered with the gold rush north of the city, and with its selection as the terminus of the Alaska railroad it became the commercial center to the interior.

But its real growth came in 1973 and 1977 with the construction of the Trans Alaska Pipeline. It was an old-fashioned boomtown - with a great deal of money about. The effects are still visible. But Fairbanks is also home to the University of Alaska.

It would be a disservice to Fairbanks to suggest that you travel 3,000 miles to see the museum at the university - superb though it is. It is rather the ability of Fairbanks - and Anchorage and Juneau - to encompass both ends of a very broad spectrum from civilization to wilderness that makes them all fascinating.