There is not much to see and to do here for an average tourist, except surfing. The two most touristic areas are both some kilometers outside of San Juan:
Urbiztondo There are several resorts in this area with rooms, restaurants and surf lessons. Resorts are quite pricey. Prices for surboards are usually about Php 200 per hour, surf lessons also amount to Php 200 per hour (Feb 2010). The swell is usually slightly better than in Montemar. The water can get very crowded, especially on weekends where you may count more than 70 surfers along the short beach.
Montemar Is less developed, fewer resorts and you have all the water for yourself. Bring your own board or choose one of the resorts that rent out boards. Resorts do cost less here on average compared to Urbistondo. Prices for boards are about Php 120 per hour. Surf lessons are not available here.
The best way to get here is by bus from Manila. Take one of the many bus lines bound to La Union. Tell the bus driver to drop you at San Juan - Sebay (Urbiztondo) or San Juan - Montemar. Both are well known stops among the bus drivers. San Juan Center has nothing to offer related to surfing.
Surf Along with Siargao, San Juan is one of the place to learn surfing in the Philippines. Experienced surfers used to Hawaiian swells will yawn but San Juan has a reliable swell of great for beginners and intermediates. Surfing Season is from November to April with reliable waves until end of January. Later there may be week-long periods without even the most minimal swell.