re: Seattle for a Day

I don't see the point to drive up the mountain and drive back down without hiking. You can see the magnitude of Rainier from the city. Just a trip to and back from Paradise will be 5 hours. In those 2 1/2 hours to get there the weather may change and make the trip pointless. Plus the wildflowers already bloomed so you missed that. There is enough to do in Seattle to keep you occupied.

Pike's Place is a must.
Underground Tour for a cool history lesson
A local coffee shop
Shopping
Take a ferry
Woodland Park Zoo (not downtown)
Check out a recreational marijuana shop (not downtown)
Chihuly Garden & Glass (near)
Space Needle (near)
Uber is awesome