I visited Sucre in March 1993 only 15 months or so after it had been "inscribed" as a WHS. For the preceding 6 weeks or so I had been in low-lying tropical areas and the weather at Sucre's 2790m altitude came as a very pleasant change.
I found it an attractive city with many interesting and buildings and a relaxed atmosphere.
I was very impressed by the Supreme Court. Not so much the building itself, which dates only from 1945, but by the ease with which I could enter and visit, and this in a country where death squads were said to stalk the land and assassination was the preferred method of settling political differences.
On the main square,Plaza 25 de Mayo, are several significant buildings. In the Casa de la Libertad the country's Declaration of Independence was signed and it was treated with appropriate seriousness by the parties of awed schoolkids being shown flags, bloodied clothing and other memorabilia of the struggle for independence.
There is a number of interesting churches in the city centre but I found getting into them quite difficult. They all seemed to have different, and very short, opening hours, with eccentric guardians, who may, or may not, open up at the advertised times.
Try to penetrate the cathedral to see the Virgin of Guadalupe studded with hundreds of amethysts, emeralds, pearls, rubies etc. It was much venerated by campesinos when I was there.
At San Felipe Neri I managed to see the cloisters and climb onto the roof to see the Penitents' Benches, though exactly what these were for I did not discover.
The museum in Santa Clara convent is also worth a visit for its eclectic mix of exhibits.
There are plenty of places to stay (I can recommend Hostal San Francisco) and to eat (eg La Taverne in the Alliance Francaise) and I was left almost entirely hassle free.
I flew into Sucre from Santa Cruz, the approach to the airport thro' the Andean hills is "exciting" and left by bus to Potosi