George Bush stated that the American people should be less like the Simpsons and more like which other famous family?

From memory, the Waltons.

The Bush-Simpson feud began began in 1990, when then First Lady Barbara Bush fired the first shot. Mrs. Bush told reporters that 'The Simpsons is the dumbest thing I have ever seen!' This unprovoked attack did not go unnoticed by the producers of The Simpsons. A few days later, an angry letter was sent to Mrs. Bush signed by Marge Simpson defending herself and her family. Two weeks later, Mrs. Bush apologized to the Simpsons and to Marge personally for 'my loose tongue.'
However, that wasn't the end. The Bush-Simpson feud was just warming up! At the Republican National Convention in 1992, George Bush Sr. told the delegates and the world that 'We need a nation closer to the Waltons than to the Simpsons!'

Matt Groening's reaction was: 'Of course you know that this means war!' Just 2 days after Mr. Bush's speech, the very next episode of The Simpsons opened with The Simpsons in their living room watching television. President Bush could be seen on the TV criticising The Simpsons for not being more like The Waltons. Bart turned to the camera and said 'Hey, we're just like the Waltons. We're praying for an end to the depression too.' (At the time, it was surprising that they were able to add something to an animated TV show in just 2 days. Animation doesn't normally work that way.)
Bart's prayers were answered. Although George Bush Sr. had an incredible 90% approval rating (according to Gallop Poll) in February, 1992; he lost the general election to Bill Clinton in November, just 9 months later.
The feud picked up again in 1996 in an episode of The Simpsons in which George and Barbara Bush move to Springfield and into the house directly across the street from The Simpsons. Although Barbara Bush and Marge Simpson got along with each other fairly well, Homer Simpson and George Bush became instant enemies.

Things got worse after Bart accidentally destroyed George Bush's memoirs, and Bush gave Bart a spanking. Upon learning of the spanking, an enraged Homer declared war on George Bush: 'First, Bush invades my home turf. Now he steals my right to raise a disobedient, smart-alecky son!' Homer yelled at Bush: 'You are a wimp!'
But Homer wasn't the only one who was mad. George Bush was also mad. He threatened Homer with: 'I'm going to ruin you like a Japanese banquet.' (A reference to the time that George Bush threw up on the Prime Minister of Japan while he was president.)
Relations between George Bush and the Simpsons continued to deteriorate until the Bushes left Springfield.

http://www.sunwayco.com/bush.html