Save money by not buying a Genie+ or save time and do it but it is not a guarantee to ride what you want at Disney.
I am not a fan of the Genie+ option. It adds up when you have multiple family members wanting it. At sometimes upward of $27.00 per person, it is a little much and you have to follow strict guidelines to get queues for the Lightning Lane. Disney says you could experience as little as only 2 attractions on a given day.
Yes, lines at Disney are long most of the time but you will find that 12-14 hours at a park is plenty to wait 90 minutes to ride an attraction and move on to the next and still take in a couple of shows and watch the parades and even eat dinner at your reservation time.
You may think you need this. You don't. Especially if you are new to the parks. You will feel pressured to get from point A to point Z and will likely miss everything in between. Take your time and enjoy. Disney is far more than an attraction or a ride. The entire park is an attraction so enjoy the entire park.