According to Politico.com, Denver-area businesses are disappointed; they don't think they'll benefit the upcoming August Democratic convention. They blame union requirements, poor communication and disorganization of the Democratic committee for the dismal prospects.
There's one more wrinkle. The presumptive Democratic nominee Senator Barack Obama will now move his acceptance speech to Invesco Field, which will increase the cost of security. Thus another item on the expense side of the ledger rather than a boost.
Measuring the costs and benefits of political conventions requires a look at what conventions displace. The key is always to make sure that business as usual occurs and that disruptions are kept to a minimum. More background on the economics of political convention can be found here.