Need advise on road trip from Palm Springs to Bellevue WA in July/Aug

[RoseGardener]

I am planning my annual migration from SoCal desert to Pacific Northwest, I realize I needed help. I have done this trip for years and explored the coastal route hwy 101 all the way; the mountain route Hwy 395 thru Yosemite/Tahoe/Bend, and of course the I-5, oh even the complete California Hwy 99.

For this year, I am debating if I should try the Palm Spings > Las Vegas > Salt Lake City > Walla Walla > Bellevue ? According to google map, this route is 1500 miles (23 hours) vs the shortest route of I-5 at 1270 miles (20 hours). I am planning to leave mid July and return in Mid Sept, totally flexible. I am a city boy, not into outdoor stuff, but into good food. Any tips, must sees? or any reason not to do this route?

This is my tentative plan:

Day 1. July 17th
Palm Springs to St George UT and stay one night, 6 hours 368 miles.
Day 2. 18th
St George to Zion Nation Park,
-take the free shuttle to explore the park (I am not into hiking),
-then drive to Bryce Canyon via Hwy 9 (2 hours 85 miles).
-Drive the Bryce Canyon Scenic Drive.
Day 3. 19th
Bryce Nation Park to Sale Lake City,
-anything must see along the way? Any alternative route to I-15?
-Attend Pioneer Day Concert-2019 Mormon Tabernacle Choir & Orchestra on Temple Square.
Day 4. 20th
Find something to do in or around SLC during the day, suggestions?
-attend Norah Jones concert in the evening.
Day 5. 21st
Salt Lake to Boise, 5 hours, 399 miles, and worthy detours?
-Attend Idaho Shakespeare Festive, The Music Man
Day 6. 22nd
Any Boise must sees?
-
Day 7. 23rd
Boise to Walla Walla, 4 hours 250 miles,
Day 8. 24th
Explore Walla Walla, any wineries and eateries recommentations?
Day 9. 25th
Walla Walla to Bellevue, anything along the way that are must visits?

Open to all suggestions.