You should also bear in mind that hotel reservation need to be booked early, because prices shoot up, the same goes if you want to rent a balcony and chairs, it is very expensive and usually have a lot of subscribers from one year to another.
Getting to experience Spanish Holy Week from a balcony is an unforgettable experience. You can enjoy privileged views, almost touching Christ or Mary as the processions pass bay. On top of that you can get catering and a private area to get together with your family and friends. This way you can avoid the crowds in the streets that enable you to properly enjoy the processions. You can also get some really good pictures from the balconies.
Further from the religious aspect, during the week you can see the streets sculptures of uncountable historical value entirely free surrounded by a mysticism halo.