Salar the Uyuni (Uyuni salt flats) is just an amazing place! We started the tour in Uyuni village. We'd choozen for Quechua Connection, because of the many good reviews.
Well, the best time to visit just depend on your personal taste. We visited this place towards the end of october, in the summer season. It tends to be Sunny and dry then. But if you want to see the mirror effect on the saltflats, you should consider coming january to march. This mirror effect is awesome too. A reason for a revisit in the future. You can visit the saltflats all day, from Sunrise till sunset they are beautiful.