You can really relax with a 3 or 4 night trip. First, do the math. Packages versus buying separately. Generally, we all suggest to buy tickets and hotel room separately. Sometimes, the Annual Pass rate at the on site hotels is really good. Only 1 person has to have the Annual pass to get the discount at the hotel.
Look at the hotel websites to get the best rate. They will show any promotions. To see if there is an Annual Pass discount, use APH in the code box. You can also call the hotel to see if any
AAA rate is available (if you have AAA).
Tickets are cheaper the more days you buy for. One of the best places to get tickets is from undercovertourist. Prices at their website include tax and shipping. AAA does sell tickets cheaper too.
My teen really enjoyed staying on site. First, the express pass you get with your stay is awesome (that includes the day you check in, days there, and day you check out). Second, staying where you are able to walk or get a boat ride to the parks is nice. The pools at the on site hotels are good too. You can even pool hop within the 3 hotels with your room card.
Generally, the Royal Pacific is the cheapest, but keep checking. Your teens may like the Hard Rock. The hotel rates do change. Note that if you see a lower rate after you book, if you call, they can ajust your rate. Last year, I took a stay more save more promotion rate at RPH, but when I saw the Annual Pass rates, for my family, it paid to have me buy an Annual pass and we changed our reservation to the AP rate with one phone call. Reservations was very nice to deal with.
Have a great time! The parks are really enjoyable to look around. The theming is good and with that many days to go to the parks, take time to just enjoy the scenery. And, if your teens are thrill riders, they will enjoy some of the best rides. Even my tween enjoys the coasters there.