Choosing a business location ought to involve lots of market research. But don't tell Lynne Holland and Linda Nath that.

"Linda kept driving past it, and we'd always talked about having a shop," says Ms. Holland. "So we never looked at anything else. It was The One."

Last year, the pair opened Treasures in Thyme, a funky antiques/consignment/gift shop in a 1946 Sears kit house on Regis Avenue in Pleasant Hills.

Leo Love also gave an odd answer when asked why he and Bill Cox chose an old house-turned-car-repair-shop on Ohio River Boulevard in Bellevue as the site for their new antique store, The Antique Mall on Ohio River.

"I just wanted to see my dining room floor again," he quips.

Many old houses have been rehabbed into modern businesses, and antiques and collectibles, in particular, seem to lend themselves to being displayed in rooms with homey architectural details such as carved wooden mantels, beamed ceilings, pocket doors and hardwood floors. What customers don't always realize is how much work it takes, often more than if the building is restored as a home.

For instance, it took Mr. Love and Mr. Cox almost a month to clear the 2¹/₂-story gabled house, which dates to 1883, of more than 400 tires and assorted car parts. Over the next six months, they pulled down plasterboard that covered most of the original windows and fireplaces, refinished its floors, installed heat and electricity on the upper floors, and pulled off the aluminum siding to expose the original red brick.

Their main goal wasn't just to create a picturesque space for selling antiques. Mr. Cox and his partner also wanted to return the house, which was built by Scotsman Alexander Gilliland, to as close to its original state as possible.

A friend and contemporary of Andrew Carnegie, Mr. Gilliland was one of Bellevue's prominent early citizens and social consciences. Gilliland's Terrace, a housing development he built on a nearby hillside, offered young married couples affordable housing. One street bearing his name has survived.

OK, so maybe that bright-purple paint job on the bottom half of the exterior isn't exactly period. But the rest of the main house speaks to a time when the Victrola was a preferred mode of entertainment (Mr. Gilliland allegedly played his so loudly on his front porch overlooking the Ohio River that people could hear it in McKees Rocks). Many rooms still hold their original ceramic tile fireplaces, and there's also working pocket doors in the main parlor, and in the dining room elegant judges paneling.

Ms. Holland and Mrs. Nath faced different building issues. While they're undeniably quaint, most Sears houses -- particularly single-story Craftsman models such as this one -- aren't especially large. To make room for customers and merchandise, the women tore down a wall between the kitchen and living room, removed doors and took out closets in two bedrooms. They also turned a breezeway between the garage and house into a room by sheathing it in barn wood, and remodeled the garage with stained cement floors and beaded-board walls. The final decorative touch: four rustic ceiling beams of rough-cut cedar two-by-fours.

"It just all came together," says Ms. Holland. "Some of our customers have likened it to a shop in Volant," a scenic village in Lawrence County.

It's not unusual for antique shops -- especially those owned by just one or two people -- to specialize in favorite types of pieces or a certain period. The philosophy at both of these stores, however, is to mix it up with a little bit of everything to broaden its appeal to a variety of shoppers.

Mr. Love and Mr. Cox have rented space in the building's dozen rooms and adjoining garage space to 21 vendors. Vintage clothing and jewelry mingle with artwork, Empire period bedroom sets, antique toys, glassware and '50s kitsch.

Retro furniture, such as a bright-orange Charles Eames fiberglass chair with a $125 price tag, are especially popular right now. You'll also find oddities such as a wooden lobster crate ($75), a black rotary telephone from the '60s ($12) and a picture of Jesus hand-painted in 1966 for Lutheran Church of Redeemer in Homewood ($125).

Treasures in Thyme leans a little more toward primitives/country and unique gift items, such as perfectly cleaned and pressed vintage linens (hand towels run about $6) and colorful McCoy pottery. The store is also heavy on one-of-a-kind pieces of hand-painted furniture, such as a 100-year-old dresser Ms. Holland finished in a pale-mint green, with cream-colored drawers. Price: $125.

Other items spotted on a recent visit included an enamel table from the 1930s ($135), an oak Hoosier cabinet ($925), a vintage Singer sewing machine ($95), a variety of enamel boxes and oil paintings, and a set of wooden Civil War heroes that were hand-carved by Pleasant Hills craftsman Ed Handshoe ($75 each).

When prices are low, says Mr. Cox, merchandise tends to move and is replaced. So every time a customer visits, he or she finds something new and different.

"The kiss of death is when you don't change," he says.

The Antique Mall on Ohio River, 4331 Ohio River Blvd., Bellevue, is open daily from 10 a.m. to 6 p.m. 412-561-6331.

Treasures in Thyme, 707 Regis Ave., Pleasant Hills, is open Tuesday through Saturday from 10 a.m. to 6 p.m. 412-655-0107.