Chicago ? The Wrigley Field bleacher bums have room to roam this year, and the high-priced club seats at Fenway Park now come with fresh air. At Petco Park, the only thing fans smell are the fish tacos.

Baseball’s building boom has slowed, and rehabbing is now all the rage. With the competition for spectators – and their money – rising each year, and municipalities less willing to hand over hundreds of millions of dollars for new stadiums, ballparks throughout the country are getting makeovers.

“Wrigley Field is, gratefully, perceived to be a very special place. It behooves us that we continually improve it and constantly make the fan experience the best we can,” said Mark McGuire, executive vice president of business operations for the Chicago Cubs, who added almost 1,800 seats to the bleachers this year. “We don’t want to go backward.”

A few years ago, two or three new ballparks were opening just about every season. While some replaced stadiums that were older than the designated hitter, others were upgrades of places only 20 or 30 years old. Teams know they have to make their new digs go further than that, which means looking for improvement potential from the moment the place opens.

And with major-league ticket prices averaging $22.21, up 5.4 percent from last year, fans expect to be entertained when they come to the ballpark – on and off the field.

“You just cannot stand pat in our industry,” said Bob DiBiasio, the Cleveland Indians’ vice president of public relations. “You need to consistently add value to the experience of customers.”

This year alone, the Cubs renovated their bleachers to add 1,783 seats along with a concourse that gives fans a place to gather, a restaurant in center field and more restrooms and concession stands. Fenway Park replaced the glassed-in .406 Club with two open-air lounges. Dodger Stadium replaced 50,000 seats, with the new ones having the same color scheme as when the ballpark opened in 1962.

The Tampa Bay Devil Rays’ new controlling owners gave Tropicana Park a spiffy new paint job, inside and out, and put flat-panel TVs throughout the stadium. The Philadelphia Phillies are throwing rooftop parties at Citizens Bank Park on Thursdays – complete with a mechanical bull. Petco Park went smoke free.

“Baseball is vying for entertainment dollars these days,” said Janet Marie Smith, who oversees the Fenway renovations as the Red Sox senior vice president of planning and development. “(The improvements) are all focused on amenities that will encourage fans to come, whether they’re the die-hard fan or somebody who’s there for an outing with their family.

“It’s an effort to keep the ballpark itself fresh and new, but also give fans a reason to make a repeat visit if it’s not the team that’s the draw,” she added. “You can’t always count on having 37,000 people who are knowledgeable about the pitcher and the bullpen.”

Fenway and Wrigley are among the few places where capacity crowds are practically a given, with fans coming as much for the park as for the game itself. The ballparks are the two oldest in the majors, and seeing a game at either is like a peek into baseball history.

Other parks – even the new ones – have to work a little harder.

After taking plenty of grief for a bland outfield concourse and upper-deck seats so steep they came with a nosebleed, the Chicago White Sox overhauled their 15-year-old park as much as they could without blowing it up. In the last six years, they’ve taken eight rows off the upper deck and replaced the ugly slanting roof with a cozy flat one. They transformed the boring concourse, and last year put in a three-story children’s area complete with batting cages and a mini diamond.