United are embarking on a new era with Van Gaal at the helm following David Moyes' disappointing 10-month spell in charge.
Under the Scot, who was selected by Sir Alex Ferguson to succeed him, United endured their worst campaign in Premier League history, finishing seventh.
Van Gaal appears to be slowly putting United back on track. The Dutchman has enjoyed a successful pre-season tour so far, registering wins over Los Angeles Galaxy, Roma and Inter Milan.
And off the pitch the players have responded well to his demands for unity, strength and commitment.
"It's marvellous. I am so pleased with the way it has turned out," Charlton, the club's record goal scorer told MUTV.
United have been quick to make their move in the transfer market this summer, sighing Luke Shaw and Ander Herrera last month for a combined fee of £55million. More signings are expected.
The Moyes era began with a failed attempt to sign Herrera and his compatriot Cesc Fabregas.
Charlton, a director at Old Trafford, concedes errors were made in Moyes' only year in charge.
"We struggled a little bit last year and maybe a few people made a few mistakes but I don't think we will make them now," said the 76-year-old, who made 758 appearances for the club.
"Hopefully we will be well-served by a really clever man."
Of the failures of Moyes' reign, the biggest was his failure to qualify for the Champions League.
Van Gaal believes his team have a chance to prove they still belong among the European elite on Saturday though when they face Real Madrid, who won their 10th Champions League trophy last term.
United will play the Spanish giants on the outskirts of Detroit, where a record 109,000 crowd is expected at Michigan Stadium, more commonly known as the 'Big House' as it is the third-biggest sports arena in the world.
A win will guarantee United a place in the International Champions Cup final - and Van Gaal thinks victory would also go some way to proving United are still a force to be reckoned with.
Reflecting on the three wins he has registered so far, the United boss said: "We played against AS Roma, who were second in the Italian league, then against Inter Milan, who were third in the Italian league.
"Now we play Real Madrid and it is nice to play against such teams, so you can show you are at least equal."
Making Monday's final, and beating potential opponents Liverpool or Manchester City to take home a prize of 1 million US dollars (£600,000), would be a perfect way to round off what has been a successful tour for Van Gaal.
After their exploits in the United States, Van Gaal will take his squad back to Manchester, where they play Valencia at Old Trafford before the season begins on August 16 against Swansea.
Van Gaal has always been a fan of the English game and he is looking forward to experiencing his first taste of Premier League football.
"I have always looked to matches of England," said Van Gaal, who lists Charlton and Nobby Stiles among his favourite United players.
"I like the atmosphere of the English games.
"To work for the biggest club in England and the world makes it more of a challenge for me."
Cristiano Ronaldo, meanwhile, has stepped up his fitness work at Real Madrid's base in Los Angeles in the last few days and could feature against his old club.