In the morning, I walked over to the central bus station and found bus 14 to the Buddha Park. It also stops at the border crossing to Thailand at the Friendship Bridge. The bus is slow but cheap and better than having to deal with the tuk-tuk drivers. The bus drivers know that foreigners are either getting off at the border or at the Buddha Park. The park is 20 to 25 km from downtown Vientiane.
The Buddha Park is purely for tourists and has little or no cultural value but it is still fun, impressive, photogenic, and worth a visit. The park isn't very big so it doesn't take long to go through it and take nice photos. The bus stop to return to Vientiane is right across the street and there is a sign.
After returning from the Buddha Park, I negotiated a tuk-tuk ride for 20k to the Wat That Luang area to see the temples and big stupa. The area is nice with all the typical stuff including a lot of souvenir stalls. I had an excellent hot curry at an upscale restaurant across the street from the complex, next to the bus stop. I took the bus back to downtown.
In the afternoon, I walked to the Wat Sisakit temple. It's a small place and hardly worth a visit or the 10k entry fee. After that I walked up the main street, Avenue Lane Xang, to the Patuxay Park which has the huge, impressive arch which is an Asian version of the Arc de Triomphe in Paris.
On the way back, I went to a tour office and bought a bus ticket to Luang Prabang for the next day. The hotel pick up will be at 07:00 for the 12 hour bus ride.