They cosy $59 each and honestly I think you can do the wizarding world without them. We saw lots of people trying to use them but they didn't always work well. My son was not that interested in the virtual wand part. The rest of the Harry Potter world was pretty cute but not mind blowing. If you get there after lunch or even after 9ish you will have to join long lines on the virtual app for the Hagrid ride. Because we got there at the opening time we were able to go on both rides straight away. My son thought it was OK but I had to close my eyes for at least half of it. Anyone who gets carsick and seasick like I do will feel really sick and dizzy on this ride. The harry potter forbidden journey was not for me. The first time I was petrified, it is really fast but the second time I just enjoyed it knowing what was coming. I generally am a scaredy-cat and don't like roller coasters but my son begged me to go on the Hagrid ride with him. We entered the park at eight when it opened and although there were still hundreds of people entering at this time we were able to go straight on the Hagrid roller coaster and also the Harry Potter Forbidden Journey ride. We were on the bus by seven and in line by 730. We were in the Dockside hotel so we had early access. We went mid week thankfully as when we left on a Saturday I could tell just at my hotel how packed it was going to be! My advice is to get there early. I went with my 11 year old son mid August. If you are not in the parks for Harry Potter world, The Hogwarts Express is still a great way to get from the back of one park to the other. There are different experiences London-to-Hogsmede and Hogsmede-to-London.
If you are in the parks for Harry Potter, make sure to get park-to-park tickets to experience the Hogwarts Express. I enjoyed it especially since you are seated more actively upright in the ride, rather than most rollercoaster seats. This was our first visit with Hagrid's Motorbike ride available. If you want to send souvenirs, you can buy postcards and send them via Owl Post with a Hogsmede cancellation on the postage. All the witches and wizards (staff) in the park are friendly and helpful. Depending on how busy the parks are, there may be short lines for these too. We enjoy the interactive wands as it gives you something to do between rides.
The larger rides (not Flight of the Hippogriff as much) have detailed queues, which give you things to see while you are waiting. The Wizarding World is incredibly well done with an atmosphere appreciable for those who aren't familiar with the world, but easter eggs for those who know the movies and especially for those who know the books.