Korean Airlines has a handful of 747-8 in active operation but they're making moves to retire them especially post Asiana merger.
Air China also operates a handful of 747-8 and 747-400 on both international and domestic routes.
FlightsFrom is a great resource to find routes for specific aircraft: https://www.flightsfrom.com/explorer/FRA?aircrafts=747 https://www.flightsfrom.com/explorer/ICN?aircrafts=747
Always fun to be on the second floor despite the seat configuration being a bit dated.
Great seat number though.
And both B747 and A380 fly much calmer than the smaller, lighter widebodies, which is equally nice for passengers on all classes.
So far my personal favorite is the 787. About the only thing 'bad' I can say about it is that all the mechanical bits are kinda loud, like the flaps and stuff, and are very noisy inside the cabin. But it cruises so nice, and the lower pressurization altitude and increase in humidity is noticeable on a long flight.
The 787 is nice but I find the seat width quite cramped in economy, and unfortunately premium economy isn't great value either to pay or for points upgrade on any of the airlines I fly...
What’s even the point of flying if you can’t look at the world from up high?
I only ever flew on the upper deck in coach configuration, and the last time I did that was about twenty five years ago on SAA. It wasn't anything special, but it was a little quieter.
It felt like a private jet up there, very cool. And that's even with the awful club world seats where you had to step over your neighbour to get to the aisle.
I would at least explore the city for a few days to have a break.
The only flying I enjoy is when I'm the one in the front left hand seat holding the yoke :)
There's still a few of these in passenger service, so you can easily get it done if it's important to you.
Otherwise, you'll need to figure out how to get on a cargo flight.
But I probably missed my chance for an A380. Maybe a Lufthansa flight will pop up that’s affordable. The other airlines mostly operate in the ME or Asia, and no plans for either right now.
I just asked my favorite stochastic parrot to find the cheapest flight from SFO on a 747 to anywhere. It found a one-way flight on Lufthansa for $500. If you can, I'd encourage you to spring for a business class flight on the top deck (probably $4000 one-way).