March is during the most expensive golf time of the year. Regular rates run from about $130 per round to $175 depending on course (that includes cart). Osprey Ridge is the most expensive, followed by Eagle Pines, Magnolia, and Palm and Lake Buena Vista, which two are usually the same cost. After 3 p.m. rates are about half the regular rates. If you have an annual pass, you can get 30% off for up to four players -- although you need to check as that discount has not yet been confirmed for beyond mid-January. There are no junior discounts (except on the Oak Trail course, a nine hole, short executive course that is walking only and is heavily occupied by kids and beginners).
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DVC member can play that time of year after 10 a.m. for $95 a round at any course. However, to get that discount you need to buy an annual DVC golf card at one of the pro shops for about $91 (which includes tax). Thus to make buying the card worth it, you need to play multiple rounds.
If you are paying regular rates, you can make tee times up to 90 days in advance, 1-407-WDW-GOLF; when using an AP or DVC discount it is 14 days that time of year. Note, it is usually fairly easy to get times up to 7 days in advance, and you can usually even get times the day before as long as you are not choosey about course and at least an hour flexible in the time you want. They play foursomes if possible and thus a twosome will most often automatically be hooked up with another twosome or two singles.
The Osprey and Palm are the most difficult courses, Lake Buena Vista the easiest, Eagle Pines is the shortest but "target" golf with a lot of trouble around greens, and Magnolia is the longest but has very wide fairways (and the Mickey shaped sand trap that you see in ads). Osprey, by far, is the most impressive course there (which is reflected in its high cost) but all are very good and well-kept.
Marc's Golf Site, which provides a lot more info, is at wdwgolf.com