With the size of your group, both Fast Lane and Fright Lane would only be $30 per a person each and (in my opinion) would both be well worth it. Otherwise, expect to accomplish very little and wait very much. Fright Lane lanyards can be ordered HERE, Fast Lane wristbands can be ordered HERE.
If you choose not to use Fright/Fast Lane, my advice would be:
If your whole group has Gold/Platinum passes, take advantage of the hour ERT at Beast and Diamondback
Even if you don't do ERT, arrive at the park before opening and try to do as many major rides as quickly as possible. This is especially true with lower capacity attractions like Invertigo, Backlot Stunt Coaster and Firehawk.
Eat lunch and dinner at irregular times to avoid long waits at the food stands
Visit more minor attractions in the afternoon while the major attractions have longer waits
When certain Haunt attractions open at 5pm, do them quickly and avoid the major crowds later in the day
Ride waits are (typically) not as long during Haunt as they are during the day. There are exceptions, but Haunt may be a good time to do anything you missed earlier
The park empties out tremendously within the last hour of operation. After 12:30am, many rides and houses have little to no wait - take advantage of this
Beyond that, simply have a good time and what-not