Demand for rooms means that rates are high at the best hotels by the standards of any major European or North American city (and factoring in the exchange rate means a hotel room can take a substantial bite out of your budget). Service charges range from 15% in expensive hotels to zero in moderate and inexpensive ones. Be sure to inquire when you make reservations.
As a general rule of thumb, lodgings on the north side of the Liffey River tend to be more affordable than those on the south. B&Bs charge as little as EUR 46 a night per person, but they tend to be in suburban areas -- generally a 15-minute bus ride from the center of the city. This is not in itself a great drawback, and savings can be significant. Many hotels have a weekend, or "B&B," rate that's often 30% to 40% cheaper than the ordinary rate; some hotels also have a midweek special that provides discounts of up to 35%. These rates are available throughout the year but are harder to get in high season. Ask about them when booking a room (they are available only on a prebooked basis), especially if you plan a brief or weekend stay.