For a single weekend event, not much, which is the problem. A bunch of one night or two night hotel stays, likewise a couple of days of keeping restaurants busy. Maybe a little pick-up at the local tourist attractions. Compare that to a World Championships T&F event where you have an influx of people staying for a week. Long hotel stays, lots of trips to restaurants, lots of free time to check out local stores and pretty much every tourist attraction in town. I'm not sure even that would be a good investment but it makes more sense than a single weekend event.
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