Evening Greeting at a Bar

You arrive at a bar in the evening and meet some people in a casual, social setting.

You
¡Buenas noches! ¿Está ocupado este asiento?
BWEH-nahs NOH-chehs! ehs-TAH oh-koo-PAH-doh EHS-teh ah-SYEHN-toh?
Good evening! Is this seat taken?
"Buenas noches" is used from sunset onward, both as a greeting and as "good night" when leaving.
Local
No, no. Siéntate. ¿Qué tal? Soy Diego.
noh, noh. SYEHN-tah-teh. keh tahl? soy DYEH-goh.
No, no. Sit down. How's it going? I'm Diego.
"¿Qué tal?" is a casual greeting meaning "how's it going?" — perfect for bars, parties, and informal settings.
You
Gracias. Mucho gusto, Diego. Soy... ¿Vienes seguido aquí?
GRAH-syahs. MOO-choh GOOS-toh, DYEH-goh. soy... VYEH-nehs seh-GEE-doh ah-KEE?
Thanks. Nice to meet you, Diego. I'm... Do you come here often?
"¿Vienes seguido?" means "do you come often?" It is a natural conversation starter and not as cliché in Spanish as it sounds in English.
Local
Sí, de vez en cuando. ¿Quieres una cerveza? Yo invito.
SEE, deh vehs ehn KWAHN-doh. KYEH-rehs OO-nah ser-VEH-sah? yoh een-VEE-toh.
Yeah, from time to time. Want a beer? My treat.
"Yo invito" means "I'm treating" or "it's on me." In Latin America, people are often very generous with invitations. It is polite to accept.