The Tulalip tribes will open their new 12- story, 350-room Tulalip Casino Resort this summer at their Quil Ceda Creek development west of Marysville. The new resort will be Snohomish County's first destination hotel. The resort opens as hotel occupancy rates have been climbing in Snohomish County. Tourism officials cite three factors: increased business travel to Boeing's Everett factory; long-term stays by construction crews working on various projects; and a growing number of Canadians coming to shop at malls north of Seattle.