Vendors will sell political buttons to collectors (does anyone wear them anymore?), and party volunteers will hand out bumper stickers (though I haven't seen many on cars anywhere this year). Party fat-cats will attend elegantly catered receptions, and those lower on the political ladder will buy hot dogs from vendors or sample local cuisine (Cuban food in Tampa's Ybor City; North Carolina barbecue).
The conventions will adopt rules that don't matter (except possibly on delegate selection), adjudge credentials with utter predictability and adopt platforms that bind no one. And of course delegates will officially nominate Mitt Romney and Paul Ryan in Tampa and Barack Obama and Joe Biden in Charlotte.
People (and the federal government) will spend very large sums of money on all this. Many will ask why we still have national conventions at all.
They are a gift, for some an unwanted gift, from history. The national convention was originated by the long-departed Anti-Masonic Party in 1831 and copied by Andrew Jackson's Democrats in 1832. After the Republican Party was formed in 1854, it followed suit with a national convention in 1856.
Until the 1960s, the national convention was a communications medium. Political leaders in the various states seldom met each other, outside of sessions of Congress, during the four years between presidential elections.
Men did business well into the 1960s in written form: They spent their days reading their correspondence, dictating replies, and proofreading and signing their letters. Long-distance telephone calls were unusual; direct distance dialing was introduced only in the 1950s.
People ordinarily didn't put in writing their bottom-line negotiating position. Recipients sometimes ignored the command to "burn this letter." Better to wait until you could meet in person, in the convention city.
As a result, even the shrewdest politicians didn't know who had how many votes until the convention roll call was conducted. Campaign managers would hold back votes on early ballots to show momentum later. "Favorite son" candidates with support from home state delegations would wait for real contenders to bid for their support.