NEW YORK - Half the respondents of a new poll say taxing the richest Americans by at least 50 per cent is a great idea, while more than a third consider Twitter a fad that will likely fade.

Those are among the findings of a new "60 Minutes"-Vanity Fair Poll released Sunday.

Nearly half of the respondents chose Wal-Mart as the institution that best symbolizes America today, leaving in the dust runners-up Google, Microsoft, the NFL, and the banking and securities firm Goldman Sachs.

Dining out was chosen most often by respondents as a luxury they hate sacrificing in these tough economic times. And 5 per cent thought the best way to fight obesity among patrons of fast-food chains is to equip each restaurant with scales for them to weigh themselves.

A politician taking bribes is considered by far the greater sin (chosen by 37 per cent of the respondents) when stacked against extramarital affairs (just 2 per cent).

President Barack Obama has set a time table for a troop pullout in Iraq by 2011. But one-third of poll respondents predicted he won't be setting a time table for removing troops from Afghanistan. Meanwhile, 31 per cent said he would time it to the beginning of the next presidential campaign, and 25 per cent chose "in about a year."

Obama was edged out by George Clooney (24 per cent to 26 per cent) among respondents choosing "which man they would most like to trade places with for a week," followed by Tom Brady and Bruce Springsteen.

But among woman, First Lady Michelle Obama was the favourite, chosen by 26 per cent, with Secretary of State Hillary Clinton picked by 16 per cent, actress Angelina Jolie by 13 per cent and singer Beyonce selected by 12 per cent.

The poll is based on a random sample of 1,097 respondents nationwide. It was conducted by phone between Aug. 27 and 31 by CBS News.