Kanye West -- All Smiles After Kim Kardashian Engagement

Kanye West strolled into his hotel this afternoon in San Francisco ... just hours after proposing to baby mama Kim Kardashian -- and the guy looked REALLY HAPPY!

West was in such a great mood all day today. In fact, the rap star even threw out a peace sign to the photogs who were snapping his pic -- it's almost like he got laid last night or something.

Congrats pal ... on the engagement (and on the getting laid thing).