Atmosphere: Relaxed, informal.

Price Range: Dinners from $3.55 to $6.25, children's menu with lower prices.

Credit Cards: American Express, Carte Blanche, Master Charge, BankAmericad and personal local checks with identification.

Hours: Sundays through Thursdays from 5 p.m. to 10 p.m., and Fridays and Saturdays from 5 p.m. to 11 p.m.

Special Facilities: Boster and high chairs.

Reservations: Advised for six or more.

When we arrived at El Sombrero on a recent Friday evening, the main dining room was full. But we were immediately shown to a table in the far corner of their smaller dining room.

This arrangement proved to have its advantages. For during the 20-minute wait for our dinner, my young sons became rather restless and spent the time bouncing to the piped-in Mexican music and munching on corn chips served with a delicious, spicy tomato sauce. The children liked the souce although it was rather hot for their taste.

Our waiter was pleasant and attentive as he patiently waited for my 5-year-old son to decide what he wanted. He finally settled on one chicken taco that was moist an good. My 7-year-old son ordered a taco plate, $2.25, from the children's menu. He said that it was okay, but liked the tacos I make at home better. And I would agree. I found the meat in my taco on my Rio Bravo combination dinner, $3.60, to be rather dry.

However, the rest of the dinner more than compensated for that.The beef enchilada and refried beans were excellent.

Grandmother ordered the Acapulo combination $3.55, and found the cheese enchilada delicious. All dinners, which include an enormous amount of food, are served with refried beans and Spanish rice. The rice i good, but a bit bland.

My daughter ordered the children's enchilada plate. She liked the rice and cheese enchilada, but wasn't fond of refried beans.

Dinner prices range from $3.55 to $5.25. The standard Mexican dishes are served - tacos, enchiladas, chili relleno, tamales, beef and bean burritos. There are many specials, including echiladas filled with Alaskan king crab covered with green sauce and garnished with sour cream; tostado, an open corn tortilla with layers of beans and spiced beef, lettuce, sweet peas, tomatoes and topped with sour cream.

A half litre of margarita is $4.00, a glass $1.50, and full litre of sangria is $3.50, a half litre, $2.05.

The restaurant, which has been at Lee Highway and N. Harrison St. in Arlington for eight years, is spacious and hospitable. The decor is rather plush - thick carpets, Mexican art work and huge Mexican hats.

We had planned to order coffee with Kahlua and whipped cream, $1.75, but were too full from dinner. The two older children each got a large bowl of orange sherbert with their dinners. I asked our waiter for an extra bowl so they could share with their little brother. Instead, he brought a bowl of sherbert to my 5-year-old, on the house.

Our entire meal, including tax and tip, came to $16.53.