Having to wait until your 12th 7 day sailing for priority checkin seems high. What if you only did 3 day cruises, it would take until your 26th cruise just to skip in line.
Most "perks" I don't care for. On my last trip I got tons of coupons and offers and didn't use any. Totally looking forward to being on top level celebrity soon though. Free morning and night party everyday with free booze/snacks. Even though I'm not a big drinker this would mean there's no reason to spend any money on alcohol.
Free laundry and internet is also a cool perk many offer.