What's the best way to insulate an attic with 2x4 joists?
Blown in cellulose can be quite effective if all air gaps are located and sealed with expanding foam for this purpose. Look for gaps around light boxes/electrical, fan vents, and those in corners. Unless sealed, you'll lose heating and waste money. If the previous fiberglass batts had dark marks, they generally indicate an air leak.
You can lay insulation batts in the directions you mentioned, but I'd go with the most effective insulation at the lowest cost. If your attic has an access panel, insure you've built a &quot;surround&quot; and tightly sealing door, as well.