THE OPTIMISM IS BEAMING like the summer sun. America’s big-company CEOs are bursting with confidence, in June expecting to take in even more revenue and make bigger investments than they foresaw in March, when they were more confident than ever before in the 15 years the Business Roundtable has been surveying them. CFOs are just as ebullient. Their perception of the North American economy was recently the highest in the eight years Deloitte had been asking about it.