What part of the country?

Second story porches where popular in the south before central air came into common use for sleeping.

the deep south

I have one on my house and I love it. I live in the northeast. My house was built by folks who did business in the south during the 1830's and they were not shy about taking what they learned about houses down south and applying it to their home in the north.
Having a upstairs porch means a little more privacy. Typically when you have a porch it has a common access area. A upstairs porch general is accessible only from maybe one or two rooms. You can personalize the area more.
I find most folks forget it's there so if you want some alone time it's a wonderful place to go.

Ours is south facing... so we enjoy the sunshine, along with tea as we read.

I had an upper level porch (and a lower level one, also) and loved it. In fact, I used it almost exclusively for sitting outside with my coffee (a.m.) or glass of wine (p.m.)--or pretty much everything.

Love it. It's like an extra room.

We call ours a deck.
;)

Older homes with their sleeping porches. Had one once and loved it. Good view, more privacy. I take it the upper level porch has a roof as opposed to a deck.