Can't say anything about the two hotels, but the Bairro Alto Hotel (note the spelling) is on Praça Camões, which tends to be loud at night. Make sure they have good sound insulation. The Ivens is on a quieter side street.
Both are nice for exploring the city, but if you're planning to uber around, expect delays getting into and out of the area - vehicle traffic is slow in this area, especially at night.
Make sure you're comfortable walking up and down hills in both cases.

Three days/2 nights is enough to see the highlights of Lisbon.