You've got a friend in Pennsylvania. All the signs tell you so and the visitors' centers will give you a button proclaiming it. The Keystone State wants us to come north to visit and perhaps we should, because they've laid on some new and interesting things for the coming season.

Gas prices are up everywhere, but most parts of the state are well within a tank of gass -- all of the state if you have already bought your gas-miserly go-buggy. In the Poconos, in Hershey, in the Penn Dutch country, in Gettysburg and Philadelphia, they're expecting bigger-than-ever crowds.

The City of Brotherly Love is getting ready for its 300th birthday party next year. It no longer calls itself Surprising Philadelphia because city officials think most of us already know that there's more than history in the nation's first capital.

To begin with, the ancient Bellevue Stratford Hotel is "new." Until November it was known as the Fairmont, but now it has taken back its old name, which was so highly respected for so many years. It has a new owner who renovated it properly, as befits a lady of a good many years. The preliminary demolition crews, it is said, used pickaxes instead of explosives -- now there's respect. Gone is the memory of the Legionnaire's disease which a few years ago took the lives of 29 visiting conventioneers and ultimately the life of the old hotel.

In 1981 the Bellevue Stratford deserves to be ranked among the finest in the country, according to Pennsylvania officials. Tea in the lobby, string orchestras, palms, elegant Sunday brunches -- stylish echoes of another era. Nice to welcome back one of Philadelphia's grande dames.

New last October was a different sort of hotel, Canadian Pacific's first venture in America, the Franklin Plaza. It's the town's largest now and reasonable, in case you're watching the pennies.

Restaurants? No longer does Philadelphia's claim to gustatory fame rest solely on the reputation of Bookbinder's. Now there's Steve Poses' Frog and, for less outlay, his Commissary cafeteria and his Eden on Chestnut Street where the price is really right and the food still tops. Some prefer Xavier Hussenet's Black Banana at 3rd and Race Sts. It's a private club, but don't worry -- you can become an overnight member complete with card for $1. This is supposed to be the only place in Philly where you can get fresh foie gras flown in daily. Latest price, with a glass of sauterne thrown in, $18. What would W. C. Fields have to say about that?

The museums of Philadelphia take a back seat to few and, until June 7th, the Philadelphia Museum of Art is hosting the largest exhibition of India art ever shown in this country. There's also a good deal of an of anticipation from the mummy exhibit scheduled at the University Museum, part of the University of Pennsylvania. You'll even see (if you want to) what one looks like unwrapped.

The Poconos, which call themselves the Near Country because they're so handy to the metropolitan areas, aren't worried the high price of gas will keep visitors away. People still want to vacation, officials say, and the Pocono's business is to make this possible. Reservations there are up 10 percent so far this year over the same period in 1980, and even more in the couples' resorts where you can take your love, loll in a heart-shaped bathtub and drink champagne.

Early spring may be the Poconos' finest hour. Even now the Pennsylvania Fish Commission is beginning to stock the lakes and streams with black bass, perch, place, bluegills and trout, and there's never been a better spot for camping. Pack your fishing rod and golf clubs and, while you're at it, your grass skiis. Grass skiing is new this year at Camelback in Tannersville, where the waterslide down in the side of the mountain has already made visitors forget to mourn the passing of the snows.

And consider the Brandywine Valley. There's hardly anything prettier than spring on the shores of the Brandywine River. Follow handsome little Rte. 100 until you come to the bend in the road at Chadds Ford and nenew your acquaintance with the renovated gristmill which is now Chadds Ford Museum. The Wyeth art on the walls inside reflects the rural Pennsylvania countryside and come April 26th, the courtyard outside made of stone from Philadelphia streets, will be the scene of a crafts fair in which 13 traditional crafts will be demonstrated. You may not have seen a tinsmith at work before, or a spinner, or a handful of other forgotten skills.

If you wait till May 22d to come to the Brandywine Valley, you'll see a display of Jacquard woven coverlets made by Pennsylvania weavers. All are from the collection of the Abby Aldrich Rockefeller Folk Art Center. Till then you can view 19th-century artifacts of grief, which our grandfathers took seriously. Among the surprises are the sketches done from the corpse, which are really quite engaging.

Harrisburg's capitol building, dedicated in 1906, is scarcely new, but it's considered the finest in the country. The folks up there have put together a nice walking tour which includes this Italian Renaissance building covering two acres and a sample of some of the other fine examples of early architecture in the capital city. If you postpone your visit till May 6th, you can also look in on Governor Thornburgh's house. The wallpaper panels, handpainted in Paris in 1826 and given by the Mellon family, alone are worth the visit.

Gettysburg is hoping to see you, too, and if you wait till May 3d, you can attend their Apple Blossom festival 10 miles north of the city on Rte. 234. Bethlehem is also throwing a party, a Bach festival on May 8 and 9 with two performances each day by orchestra and choir. Pittsburgh is inviting people to a folk festival on May 12-24, when national groups from various parts of the world will be turning the city into an international party with dancing and feasting.

Bucks County? The nice thing about Bucks County is that it doesn't change much and nothing gets spoiled by progress. Bucks is famous for its inns, and the inn at Phillips Mill, the Black Bass Hotel and the 1740 House (both the latter in Lumberville) are still packing them in. If you feel in the mood for a bucolic Pennsylvania weekend, reserve ahead.