Packages can be nice for several reasons. One, you put a down payment on it months ahead of your trip and pay it off as you go, so it's all paid for (including meals if you like) when you're ready to leave. You may get some extra perks like a gift card or vip seating. If you like mementos, you usually get some with a package (luggage tags, hard tickets, lanyards and pins). It all comes to your house in a neat little folder. Sometimes (rarely), the cost is less or comparable to booking on your own, especially if your party is larger.
I've found that it can pay off to book a Costco package if I'm traveling with my whole family (5) because of the free meal vouchers included. We're all considered adults according to Disney so 5 adult meal vouchers is worth over $200, which can be used almost anywhere (not just on character meals). I think they're currently offering $40 and up gift cards, depending on the number of nights you'll be there. You can also subtract the cost of tickets from your package for those who may have APs. That's a handy thing to know; you do have to call to do that. I always have an AP so I can take off the ticket charge for me.
Most of the time, though, it doesn't pay for me to book a package. I always check because sometimes I save money, but generally it's cheaper for me to book separately, especially when good discounts are offered. You can still pay off much of the trip before you go if you want, but you don't HAVE to, which is nice.
It just depends. But do bear in mind that you'll have to pre-pay your package. Booking separately, you'll have more flexibility in terms of changing dates or canceling.
