GROTON -- The rain fell in thick sheets on Monday. But it was summer business as usual at Johnson's Ice Cream restaurant on Route 119, where a mix of travelers and locals were eating their ice cream indoors.

Part of the pleasure of a visit to Johnson's is standing in line reading and re-reading the list of flavors while waiting for a turn at the counter, and afterwards, going around to the back of the building to sit at a picnic table under an umbrella, set up on the patio or the hillside that stretches into woods.

Peter and Phyllis Gingriss, who earlier in the day had taken a flight from Houston to Logan International Airport and were driving a rental car to Rindge, N.H., were sitting inside at a booth, enjoying cups of homemade coffee cookie dough and chocolate fudge ripple.

"There's a heat wave and people are lined up outside the ice cream and frozen yogurt stores," Phyllis said after she was asked about the effects of weather on ice cream consumption in her home state.

Her husband, Peter, was eating coffee cookie dough for the first time.

"I've never been to a place with so many flavors," he said. "In Houston, we have Baskin Robins with 31 flavors. That's it."

Behind the counter, Erin Keady, 17, was scooping chocolate chip ice cream into a paper-wrapped cone.

This is her third summer working at Johnson's.

"Oreo is my favorite. It has been ever since I was a little girl," said the teenager, a student at the Academy of Notre Dame in Tyngsborough.

Johnson's is both a restaurant and ice cream bar. It is located at 164 Boston Road (Route 119) and open seven days a week, 6 a.m. to 9 p.m. It's a popular place with families on summer evenings after ball games and with just about everybody else in town. There are often lines.

"It's the ideal summer job because you stay busy all the time," said Erin Keady. "I just love it."

Customers have an almost endless variety of flavors to choose from. But scooper Rachel Burnham, a Middlesex Community College student who works at the restaurant year-round, said vanilla fudge brownie seems to be the biggest seller. Scooby Snax, a mixture of vanilla, chocolate, caramel, Oreos, and Health Bar Crunch is the most unusual flavor, Burnham said.

"I've tried a lot and there a couple that are my favorites: vanilla fudge brownie and banana," Burnham said.

Dr. Davis Ice Cream at 67 Hollis St. in Pepperell is open from noon to 10 p.m. every day of the week. It's a family business owned and operated by Bill Graves with his wife, Rose, and son, Phil, the ice cream maker.

"I started working here in high school and continued through college. My husband bought the business and I've been here ever since," said Rose.

Phil Graves is the brains behind imaginative flavors such as Grahamtastic, an ice cream that tastes like graham crackers, raspberry truffle, salty caramel with chocolate-covered pretzels, and peanut butter moose tracks.

"We try to go with the trends," Rose Graves said.

In downtown Pepperell, the Rail Trail ice cream window at Charlotte's is always hopping when rail trail enthusiasts hit the popular bike and walking path.

What's popular at one ice cream stand, however, may not attract the same devoted following at another. Take Cherry Hill Ice Cream at 826 Leominster Road in Lunenburg, where the top favorite is cookie dough and the most unusual flavor is Monster Mash, a mix of Oreo ice cream, caramel swirl, and M&Ms.

"My favorite is cherry moose tracks, without a doubt," said Leanne Fagan, an employee in her 15th year with the business. "It's just really good."

In Townsend, you'll find the Ice Cream Factory, a longstanding landmark in the town's center, and Cherry Hill Too in Townsend Harbor, both strong draws to area ice cream lovers. 

The Kimball Farm ice cream stand in Westford, located at 400 Littleton Road (Route 110), ranks vanilla as its top seller. "Berry Spangled Cheesecake for Fourth of July -- cheesecake ice cream with strawberry, raspberry, and blueberry is our most unusual," said employee Jan Quinn, a fan of butter pecan, a favorite since she began working for the business 16 years ago.

At the Kimball Farm ice cream stand in Lancaster, coffee Oreo tops the favorite flavors list and frozen pudding takes the prize for most unusual flavor, said employee Meghan Connor, a loyal fan of Kahlua Crunch. When it's hot, Connor said, customers typically favor cups over cones, to avoid sticky fingers and dripping.

Likewise, what customers have to say is almost always short and sweet.

"This is wonderful!" said Peter Gingiss.