Konichawa.

I introduce you some options,which I found through https://www.rome2rio.com/s/Salt-Lake-City-Airport-SLC/Mount-Pleasant-UT-USA

There are 6 ways to get from Salt Lake City Airport (SLC) to Mount Pleasant by train, taxi, tram, bus, car or towncar
Select an option below to see step-by-step directions and to compare ticket prices and travel times in Rome2rio's travel planner.

RECOMMENDED OPTION
Train, taxi via Highway 198 @ 502 W • 4 h 25 min
Take the train from North Temple Station to Provo Central Station 750 Take a taxi from Highway 198 @ 502 W to Mount Pleasant $126 - $156
CHEAPEST OPTION
Towncar • 2 h 1 min
Take a town car from Salt Lake City Airport to Mount Pleasant 105.9 miles $16 - $180
4 ALTERNATIVE OPTIONS
Line 704 tram, bus, taxi • 4 h 34 min
Take the line 704 tram from Airport Station to West Valley Central Station 704 Take the bus from West Valley City to Payson, UT Take a taxi from Payson, UT to Mount Pleasant $148 - $186
Amtrak Thruway operated by Greyhound, line 821 bus, taxi • 4 h 56 min
Take the Amtrak Thruway operated by Greyhound from Salt Lake City, Greyhound Bus Station, UT to Provo Take the line 821 bus from Provo Central Station to Highway 198 @ 502 W 821 Take a taxi from Highway 198 @ 502 W to Mount Pleasant $140 - $182
Drive • 2 h 1 min
Drive from Salt Lake City Airport (SLC) to Mount Pleasant 105.9 miles $10 - $15
Train, taxi • 3 h 8 min
Take the train from North Temple Station to Provo Central Station 750 Take a taxi from Provo Central Station to Mount Pleasant $146 - $176 Quickest way to get there.

I hope that these information are helpful.

Junko

Salt Lake City is a beautiful place for the outdoor enthusiast as well as city dwellers. Below are approximate pricing for recommended hotels in downtown. These all received a minimum 4 star rating and close to attractions. There are other more budget friendly hotels in the area if you are interested however they may not be located in as desirable of a location and thus I have not included them.

Hotels: all prices are per day
Marriott City Center - approximate $250 during week, $150 over the weekend (Friday-Sunday)
Hotel Monaco - week day $170-$300, weekend $150-200
The Grand America - similar pricing to above mentioned hotels
Hilton Salt Lake City Center - similar pricing as above
Salt Lake Plaza Hotel - week day $130-$150, weekend $150-$170

Bonneville Salt Flats:
Approximately 1 hour and 30 minutes from downtown salt lake and is accessible by car. If taking taxi or other shared car service (Uber or Lyft) you will have to ask them to stay as you explore as there are no other facilities (stores/bathrooms) at the flats. If you go during an event (example: speed racing) there will be restrooms, shops, and food venders. Below is a link with more detail about the flats as well as other areas you may be interested in visiting during your stay.
https://www.visitutah.com/places-to-go/state-and-federal-recreation-areas/northern/bonneville-salt-flats/
P.S.
The General Conference of Mormon Church is held on October 6th and 7th. It might better to make reservations earlier if you travel around these dates.