Work has stopped on a 40,000-square-foot conference center planned for Roseville. The city-funded project was supposed to serve as a springboard from which Placer Valley would dive into branding itself as a premier business and sports tourism destination. Now, city planners are in a holding pattern, waiting for timing, funding and manpower to realign, so the region can move forward with its plan to compete in California’s massive tourism market, which, in 2007, accounted for $96.7 billion in consumer spending.