Kim Kardashian & Family Head to Bezos and Sanchez's Pre-Wedding Bash

The KarJenner clan might be going to the wedding of the century ... but, they won't be playing second fiddle to the bride and groom -- 'cause they're already stealing a ton of attention with their fashionable looks!

Kim Kardashian led the group out of a swanky Venetian hotel, slithering through the streets in a gorgeous low-cut, snake-print ensemble ... kicking off the festivities for Jeff Bezos and Lauren Sanchez.

KK and her sister Khloé Kardashian -- clad in a tight silver-and-black cocktail dress -- were throwing up peace signs as they floated down the canal in a little boat while a pal took a pic of them.

While the elder Kardashians stuck to darker colors, Kendall and Kylie Jenner channeled their flowery personalities into their outfits.

Kendall threw on a floral-print outfit that screams Southern European vacay ... while Kylie went with a bright yellow outfit that looked molto bene. She sipped on something while she took a walk, too.

Celebs have flooded Venice today ... with Jeff and Lauren giving a wave while heading to their rehearsal Thursday afternoon.

Everyone from Orlando Bloom, Tom Brady, Scooter Braun, Leonardo DiCaprio and -- obviously -- the Kardashians are in attendance. And, it's definitely worth their time ... because the couple's reportedly spending upwards of $50K on each guest in attendance.

BTW ... sources told us guests have to give up their phones for this event they're headed to -- so, don't expect to see the Kardashians sharing a bunch of pics.