Two days is probably sufficient to see Vientiane's sights. Highly recommended on your list should be the museum of Lao art, housed at the Haw Pra Kaew, and the socialist-era Lao Revolutionary Museum. The placid Buddhist monastery known as Wat Sisaket offers a good half-day diversion, and you should take a ride out to That Luang, Laos's most important religious building, to admire the effects of a sunset on its golden surface.
A popular day-trip destination is Xiang Khuan or the "Buddha Park", a Hindu-Buddhist fantasy in ferro-concrete on the banks of the Mekong River. The Patuxay victory monument is a peculiarly Lao version of the Arc de Triomphe. The Morning Market has a full city block of goods to explore. There is a tourist information office on Lane Xang Avenue just north of the Morning Market. And the Mekong, lined with picturesque colonials and cozy thatched bars, rolls through the very heart of the city and glows pink at sunset which is not to be missed.