Well, you don't multiply by 8.
You multiply by the number of rooms you will need total. Each of the packages will come with the miles so if you order say 4 packages for 4 rooms you will also get 70K x 4 miles (or more if you pick a higher award). If you have no other air miles independent of these awards, that will leave you 4x 70k short. You might want to take the award with 120k miles (270k points) but that will also leave you short by 80k miles to get free tickets for all 8 so you might have to buy one. USAir may also have a way to buy miles to reach the award level required.