From Thursday through Sunday it's as if there's a celebration going on nearly everywhere in San Juan. Be sure you dress to party, particularly on Friday and Saturday nights; Puerto Ricans have flair, and both men and women love getting dressed up to go out. Bars are usually casual, but if you have on jeans, sneakers, and a T-shirt, you may be refused entry at nightclubs and discos.
Well-dressed visitors and locals alike often mingle in the lobby bars of large hotels, many of which have bands in the evening. Some hotels also have clubs with shows and/or dancing; admission starts at $10. Casino rules have been relaxed, injecting life into what was once a conservative hotel gaming scene, but you still won't be allowed in if you're wearing a tank top or shorts. There are more games, as well as such gambling perks as free drinks and live music.
In Old San Juan, Calle San Sebastián is lined with bars and restaurants. Salsa music blaring from jukeboxes in cut-rate pool halls competes with mellow Latin jazz in top-flight nightspots. The young and the beautiful often socialize in Plaza San José. Mid-January sees the Fiestas de la Calle San Sebastián, one of the Caribbean's best street parties.
Young professionals as well as a slightly older bohemian crowd fill Santurce, San Juan's historical downtown area, until the wee hours. The revitalized Plaza del Mercado (Calle Dos Hermanos at Calle Capital) has structures—many painted in bright colors—dating from the 1930s or earlier. On weekend nights the area's streets are closed to vehicular traffic. You can wander from dive bars to trendy nightspots and sway to music that pours from countless open-air establishments and the marketplace's front plaza.