I would recommend that your first stop be with someone who preserves old photographs, paintings, and such. They can help you by stabilizing the paper the maps are printed on. Then they can also recommend putting them on a acid free linen or some such to strengthen them further thereby helping them to be preserved. Contact a museum to get names of people that are local to you who can do this. It won't be cheap but if these maps mean a great deal to you, you will find it worthwhile. If you don't plan on keeping or restoring the maps after you have them scanned, I would recommend either donating them to a museum, or if they are truly old (usually >150 years old) getting an estimated value on them and the thinking about selling them through an reputable auction house such as Southby's.