In my experience, anything that makes running your inn easier is helpful. From a reservation point of view, make sure it has an availability calendar so people can browse for openings. Many of the cheaper ones just let you type in a date range and it responds whether there is an opening or not. To me this is unacceptable.

Look for one that integrates as many of your tasks as possible. Avoid one that forces you to use one part to record your reservations and the makes you use other software to print up registration forms or guest statements. That just means you waste time moving data from one program to the next. We have been really happy with SuperInn. We've been using it for two years now and have no complaints at all.

Most people I know like Webervations. They are very inexpensive. People can book online, and you can set how the bookings are made.