Posted in the other place, but reposting here just in case it gets lost or deleted. The original question was what to do in Salt Lake City over a three-day weekend, preferrably with no car. This was my answer. It's a little out of date, but I think still relevant for people looking for travel advice. What do you all think?
Yes, there's plenty to do in a 3 day weekend.
Realize that if you really want to get a feel of SLC and why people live here, a significant portion of that is outdoors stuff. You can do some non-outdoors stuff, and there's cool non-outdoors stuff to do, but my and large that's not what makes SLC, SLC.
That said, here's a draft 3-day weekend itinerary for a "random" 3 day weekend. I'm going to assume it's not July 4th or the 24th (our local holiday, called "pioneer day") and it's not going to be in the middle of winter, where it's not very pleasant to be outside.
Friday:
Arrive from airport. Take light rail to downtown hotel.
If you get in early enough, eat a late lunch at Reg Iguana (it's on the light rail from the airport). Ask for the mole sampler; order something with mole on it. (I'm not going to do a ton of restaurant recommendations here, because a lot will depend on where you go and when, and others might have even better recommendations, but this one is sort of iconic SLC.) I suggest late lunch because they're incredibly busy during "normal" dining hours, especially on weekends. It it's too long, you can go down to Red Iguana II, which is a short walk away and serves the same food (without the same atmosphere).
Explore the Gateway area (on the light rail, but also a pretty easy walk from most downtown hotels.) It was a premiere "open air" shopping destination constructed for the olympics, but has been eclipsed for shopping by City Creek Center (owned by the LDS Church). But it's been reimagined as an entertainment destination, and there's fun stuff there. Check out Hall Pass for a communal eating and drinking experience, or one of the many (decent) restaurants in or near Gateway. Stroll through the unique shops that have come back, swing on the swings, watch the fountain, catch a comedy show at Wiseguy's, a rock show at the Depot, a laser show at the planetarium, or just a movie at the theater.
(There are other live music venues, clubs, and bars near the Gateway, if you'd rather party)
Saturday:
A.M. If you're here in the summer, go to the S.L. Farmer's Market. Walkable or a short scooter ride, it's quite large, and while it mostly features local produce and meat, there is a good selection of prepared foods or artisan crafts. Just a pretty good time.
If not, maybe a bus tour. (I've not taken them, but I think this would get most of the "sights" out of the way, with some explanation about the city and its unique history).
(You can also do a lot of these things on your own... like the Tabernacle Organ concert is at noon and is free. But this packages it nicely: https://www.saltlakecitytours.org/tours/ultimate-salt-lake-city-tabernacle-organ/)
Afternoon.: Spend a little bit of time at Temple Square. Even if you're not LDS, there's interesting stuff to see, and the missionaries won't bother you if you just say you're not interested. There's also genealogy research at the Family History Library, which can be cool. Alternatively, check out the downtown museums, including the Leonardo (an art-meets-invention museum), or the Utah Museum of Contemporary Art. If you're willing to take a little bit of a bus ride (or another Uber), check out the Utah Natural History Museum. It's on the backside of the U of U campus, and there is a bus (but service is spotty!), but it's an amazing museum. If you like dinosaurs even a little bit, you'll be in awe of this place. There's other really interesting natural history exhibits too, and it's a working research institution (you can often watch researchers carefully chipping rock away from fossils for study).
Evening: "An Event." Depending on when you come, this would include a Jazz Game, a SL Bees (AAA Baseball) Game, a Real Salt Lake (MLS) game, a Utah Symphony (full-time, amazing group) concert, a Utah Opera performance, a Ballet West (one of the best ballet companies in the U.S., featured on reality TV shows) performance, some other event at Vivint Arena (massive concert, etc.) Utes football game, Utes gymnastics meet (not always on Saturdays, and often during the day, but I'd be remiss if I didn't mention it), or a performance at the Eccles theater (broadway-like stuff). Everything except the Utes stuff is on the light rail or easily accessible downtown--even the Real SL match, which is way out in the suburbs but right on the light rail that also goes downtown.
Sunday:
A.M.: Travel to Liberty Park (not super convenient on busses, but there are ways to make it work, or a really quick, cheap Uber). Hang out at the park, walk around, check out Tracy Aviary (a bird sanctuary within the park that is cool in and of itself). Before or after, have brunch at one of the many brunch spots around the park.
P.M. Rent a bike, use bike share, or use a scooter to do a pub crawl on the west side of town. You might want to start toward the south side (Level Crossing is my favorite) and ride toward downtown. This could easily take all the afternoon into the evening. Maybe finish at Red Rock, a brew pub downtown that also has really good food.
Crash.
Monday:
AM: Short hike. You can try City Creek/Memory Grove near the capital (easy walk or scooter ride), or Ensign Peak (Uber for sure--a short but kind of strenuous hike for a really good view of the Salt Lake valley) or "the Living Room" (longer hike on the east side of town near the University--pretty much would have to take an Uber--but get really cool views of the valley).
PM: anything that I doubled up before that you didn't get to. Shopping at City Creek (it's mostly standard mall stores, but has a river running through it and is quite pleasant) or grab a souvenir at one of the many souvenir shops downtown.
Evening: Light rail back to airport.
Things not on the itinerary but could be if you were so inclined:
Downtown library (it's got cool architecture, and there are usually things going on there, but it's mostly a city library, and lots of unsheltered folks hang around a lot)
"This is the Place" heritage park (more info about Mormon pioneers, but pretty hard to get to without a car. Not so much for adults)
"Sugarhouse" (a neighborhood in the southeast corner of SLC. There's a nice park, and some local shops, and some good breweries and pizza places, but also some generic commercial development, like a Whole Foods and Old Navy. It's a nice park to run around, and there are a few hidden gems, but it's more for residents than tourists. It's accessible on public transportation, but would take you a while)
Red Butte Garden. A nice, outdoor garden for walking or enjoying good weather. It's close to the natural history museum, so not great for public transit, but doable. Can get really really hot in the summer.
Park City (not really accessible by public transit, there's a commuter bus that runs, but I don't know what weekends or holidays are like. It's a very cool, very rich, mountain town. And once you get there, public transit is free.)
Olympic Oval (ice skating and curling olympic venue) and Olympic Park (Park City -- ski jumping venue with outdoor ropes courses, bobsled, mountain slides, ski jumping shows, and more in the summer). Impossible to get to on public transportation, not so much fun by yourself. But the Olympic Park has fun events.
Ski resorts. There are ski busses if you go in the wintertime but they don't run in the summer. In the summer, there are hiking trails, beautiful mountain lakes, wildflowers, a fun Octoberfest in September, etc. "Outdoorsy" but iconic SLC and doesn't have to be too intense (also a lot cooler up there in the summer).
If you're a museum goer, check out the Salt Lake Connect pass. You can get into many of the venues I've talked about for a fairly low price. 1-, 2-, and 3-day options available.
https://www.visitsaltlake.com/things-to-do/tours-experiences/visit-salt-lake-connect-pass/#venues