Years ago, when Jed and the rest of the Clampett family moved to a rambling mansion in Beverly Hills, they were surprised at its vastness. Today, average homes are looking more and more like the Clampett's digs. Rooms are getting bigger and more lavish. What's the latest? A big deck? Home theater? A bathroom spa? They're already in place! What you'll be seeing soon is a laundry room boom. Homeowners no longer are satisfied with a simple washer and dryer in a utility closet. Instead, studies indicate two of every three homeowners now are partial to spacious, attractive laundry suites with big open areas and plenty of work space such as center islands for folding, built-in ironing boards, counter space for projects, a television set and a desk with a computer.