Elizabeth "Boo" Thomas has spent her career as a planner.

She's known for thinking through every possible outcome, talking to people with differing opinions and drawing up multiple renditions of plan A, B and C. But her recent decision to retire from decades as a nationally recognized smart growth planner was a rare instance of spontaneity.

The nonprofit Center for Planning Excellence board, which Thomas founded in 2006, announced Thursday that she'll retire at the end of the June. A whirlwind solo trip last year to Botswana, Africa, convinced Thomas it was time for a change.

The 73-year-old mother of three and grandmother of six loved the African morning light, the expanses of nature, the animals and the local people. She' been telling people for years she wasn't ready to retire yet. But she woke up one morning shortly after returning from Botswana and knew she was ready to take some more trips and spend more time with her family.

Thomas leaves a legacy in Baton Rouge of several successful planning ventures. She championed the 1998 Plan Baton Rouge master plan that ushered in a new era of downtown growth; the 2007 Louisiana Speaks Regional Plan for statewide hurricane recovery; and the creation of CPEX, which has grown immensely over the last decade.

"Anyone who's met Boo knows she's super personable, very persuasive, and in a nice way, relentless," said John Fregonese, president of Fregonese Associates planning firm in Oregon. Fregonese, who oversaw the city-parish's comprehensive plan between 2009 and 2011, had first met Thomas in 2005.

"When she puts it in her mind to accomplish something, she does it," he added. "But she doesn't always get the credit, and doesn't need the credit."

A native of Abbeville, Thomas used to be a stay-at-home mom involved with her children's activities and volunteer work. When her teenage daughter took an aptitude test that showed her potential for success as an architect or landscape architect, Thomas decided to take the test for herself. It yielded similar results.

"I always said, 'I will never work full-time,'" Thomas said Thursday. "Now, I always work overtime."

Thomas was in her late 30s when she went back to LSU for a master's in landscape architecture. It took her seven years to finish, and she wrote a thesis about connecting bike trails through communities with schools and parks. She joked about how she knew she was pursuing the right field when she saw workers pouring concrete one day and grew excited.

And she described her delight when Baton Rouge Area Foundation President John Davies reached out to her in the 1990s and asked her to head Plan Baton Rouge. She said she is still proud of the support the plan received during a 1998 presentation, and people in Baton Rouge started to realize the potential in downtown.

"I was taken by her wonderful capacity to bring people with conflicting points of view together and having them singing harmoniously in a choir," Davies said Thursday.

Davis Rhorer, executive director of the Downtown Development District, agreed. He said Thomas brought enthusiasm to Plan Baton Rouge in 1998, which has spurred restaurants, hotels, retailers and residences to open downtown in recent years. Plan Baton Rouge will celebrate its 20th anniversary later this year.

"It was an experience that forever changed the way we look at planning in the city," Rhorer said Thursday.

Thomas noted that four Baton Rouge mayors and four state governors also carried out the plan. East Baton Rouge Mayor-President Sharon Weston Broome thanked Thomas for her "visionary leadership" in a statement Thursday.

Plan Baton Rouge grew to become CPEX after Hurricanes Katrina and Rita devastated the state in 2005. Thomas began working on a Louisiana Speaks plan, showing how the state could rebuild and also look to the future. But the statewide work required a bigger entity and more encompassing name than "Plan Baton Rouge."

CPEX received its IRS nonprofit approval in 2006. The organization has become a source for municipalities throughout the region as their leaders look for help with master plans. It has tripled in size.

"Boo has been instrumental in advancing quality of life issues for not only the citizens of Baton Rouge, but throughout Louisiana," Broome said.

Thomas said the CPEX board, which has previously discussed a succession plan, will determine who will take her place.

In the meantime, she is back to making plans for an "Eat, Pray Love" type adventure. She dreams about renting an apartment in Lake Como, Italy or on the coast of France. 

"It's just so fun to have the freedom to say, 'What do I really want to do?'" Thomas said.

Follow Andrea Gallo on Twitter, @aegallo.​