Book accommodation for the full week before you arrive — then negotiate
Seven nights in one hotel is enough leverage to ask for a weekly rate. Call the hotel directly rather than booking through an OTA: smaller boutique properties in Realejo and near Plaza Nueva will sometimes offer 10–15% off the nightly rate for a seven-night stay, a reduction that rarely appears on Booking.com or Expedia. Check availability online first so you know the listed price, then ring the front desk and ask. The worst they say is no.