In general, most of Austin is pretty safe for walking around at night. I would, however, stay away from “Dirty Sixth” (the part of 6th street between Congress Ave. and I-35). This tends to be the realm of young folks looking for shot bars. To the extent Austin nightlife gets aggro, this is where it tends to happen.
I would gravitate towards Rainey Street area, downtown/west 2nd, 3rd, 4th streets, west 6th street (roughly along 6th street from San Antonio west to MOPAC – although the offerings west of Lamar get fewer and farther between), SOCO (South Congress from about Academy south to Johanna), and the Eastside (starting at about Comal and going east to about Chicon along 5th, 6th, and 7th streets.
If you want to walk from a hotel, the downtown/Rainey Street/2nd-3rd-4th street areas are pretty accessible from the downtown hotels (2 Marriotts, the Stephen F. Austin Intercontinental, 4 Seasons, the Driskill). You could probably do these areas from Rainey street as well – staying at the Fairmont or the Hotel Van Zandt. Other areas probably require a car or Uber ride to get to from downtown (or to get to downtown from those areas). The additional benefit of staying downtown (or in the Rainey street area) is that you can walk the trail along Town Lake (an ~10 mile loop right in the middle of Austin).
As to good restaurants, I recommend the following:
Emmer & Rye (Rainey street area)
Lenoir (on South 1st street)
ATX Cocina (downtown on west Cesar Chavez)
Comedor (corner of Colorado and 5th)
Qi or Lin Asian (Qi is on west 6th at Bowie, Lin Asian is farther along on west 6th at Harthan) These are owned by the same folks. Qi is fancier, Lin Asian is more casual. Both serve more or less the same stuff – delicious Chinese food – especially the soup dumplings (Yum!)
Red Ash (downtown)
Terry Black’s (BBQ just south of Town Lake on Barton Springs Road, my favorite BBQ in town)
Il Brutto (Eastside along 6th street)
Nightcap (west 6th street at Pressler – kind of half bar/half restaurant, not fancy food but delicious and nice folks – this was our neighborhood spot before we moved farther into downtown in December)
A couple of cool bars (at least they were prior to the pandemic keeping me from going out to bars):
Small Victory (on 7th street just east of the Stephen F. Austin Hotel)
Garage bar (on Colorado b/t 5th and 6th streets, in a parking garage)
The Domain also has a lot of restaurants/bars, but is a little bit too “Outdoor Mall” for me.
I’ve tried to recommend more “upscale” spots, but if you want some reccos for old-time-Austin-dive-spots, let me know.