During the night, miss 6th. I'd recommend the Domain, Rock Rose to be exact. Plenty of shopping, restaurants, (rooftop) bars, in a clean, safe, environment. Decent police presence, no pan-handlers.
https://austin.eater.com/2016/1/11/1...main-rock-rose
If Ramen is your thing, Jinya (casual) is your place. They're open until 1am on Fri-Sat. Culinary Dropouts (casual) is good, as is 2nd Bar + Kitchen (a little less casual and a bit more intimate) and Yardhouse (casual). Most of these places are open until 1 am, and have a wide dearth of palatable options. Kung Fu Saloon is a great place to grab something to drink, and 77 rooftop lounge is a nice way to spend the night.
While you're here, if you're getting In-And-Out, try a Whataburger double meat-double cheese w/jalapenos. Get the onion rings, although you can't go wrong with the fries
Mt. Bonnell will offer some fantastic views of the city, especially @ night. Most people, when they climb to the top will keep going straight to the wooden trusses, and it's a nice view, but if you make a left, there's clearing you'll get to and the view of the city is awesome.
For something a little farther north that definitely won't be busy (or hot), try Innerspace Caverns
https://innerspacecavern.com/
Round Rock honey offers tours and tastings and they have some open slots that Saturday
https://roundrockhoney.com/honey-house-tours. I think the tixs are $20, but there was a Groupon for $10 that might still be active.
The F1 fan experience will be going on downtown race weekend, and it's fun, but PACKED.
Zilker Botanical gardens is another spot that you'll enjoy, especially the wife:
http://www.zilkergarden.org/
Having visited Dallas' Aquarium last week and Austin's Aquarium prior, I can *definitely* say that the Dallas experience was better.
While the sunset view @ the Oasis is spectacular, the cuisine, sadly, is far from it.
There are plenty of places to rent a paddleboat, paddle board, or canoe on Ladybird Lake (formerly Town Lake.)
Hope you have great visit
