I visited ASU once or twice a year for business for a 10+ years before covid. I always enjoyed it. I found it calm, safe, economical, and enjoyable. Loved the Crowne Plaza and the surroundings downtown. I no longer visit unfortunately, but my former colleagues that still do all say it is all better and nicer. A lot of new infrastructure downtown along the river.

Honestly, not sure how much there is to do as a tourist, but maybe you've checked off all the other bigger attractions in South America.

Asuncion is in the southern hemisphere and July is the coolest month.