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If you are staying at the same hotel, call and speak with the manager about getting a discount. Often times, they will offer a corporate discount.

Also make sure to check out the local regulations for long term stays where you are visiting. In some areas of the United States for example, after 30 days it's no longer a hotel stay but a rental, and they do not charge hotel tax on rental. Depends on the local laws, but some areas will not charge tax for the first 30 days if they know you will be there over 30 days, others have to charge the tax.