[Bonny]

We have been on 60 plus cruises mostly Celebrity & Royal Caribbean. We think it's a great deal.
We have booked with agents & through the cruise line. Both have advantages.
You don't have to pay anymore once you get on the ship, except gratuities.
Of course there are extras if you choose. Casino, spa, shopping, specialty restaurants & coffees, wifi, shore excursions, photos & of course drinks.
Hubby & I always get the drink package. I like my premium martinis, scotch, Grand Marnier & the included fresh orange juice & specialty coffees. It is well worth it for us.
Cruise Critic is a great place to find info or talk to some of your friends that cruise.
Also, not all cruise lines are created equal. Some are better than others depending on what you like.