Your vacations sound like our vacations.
Spent a long weekend in Cleveland last month. The city gets a bad rap from Pittsburghers like myself, but it has a lot to offer, especially if you like to eat and drink. If you go to a Guardians game, you can combine it with a pregame meal and/or beer at Great Lakes Brewing Co. They have an excellent restaurant to go along with their superb craft beer, nice outdoor dining option and a free shuttle to and from the ball park. I also recommend a visit to Little Italy if you like Italian food. Lots of dining choices there. Breakfast or brunch at Lucky's Cafe is a must, too.
We had plans summer of 2020 for 2 weeks in Greece (most of it on Rhodes, where my wife's father is from), but of course had to cancel. Haven't been able to reschedule. Maybe next summer.
Wife wants to do a long distance train. If you do any of the train trips you mention, I'd be interested in hearing about the experience.
Good recommendations, I've had a few Great Lakes Brewing co beers and I do like going to breweries. My gf's (no pics) family is all from Greece and she spent about a month each summer there, just hadn't been back for several years. I did some initial flight searches a month or two back but was a bit discouraged by the prices, will look again and may just blow my points/miles.
I actually have done each of those routes twice each. Chicago to SF, Chicago to LA and Seattle/Portland to Chicago. All of them in what Amtrak calls a "Roomette", basically two chairs that face each other, they fold down into a bed, and on the top another bed folds down to sleep two. You can bring your own booze onto the train if in a sleeper car.
It's fairly comfortable during the day for two and quite a bit cozier at night. Within your train car are a couple of showers and a few toilets in the lower level. Each of your meals are also included in the price of the ticket, and the meals in the dining car are actually pretty quality given the context and a bit of fun given the context.
There's also a nice sightseeing car with floor to ceiling windows, different seating styles, kind of lounger type chairs and also bench/table set ups. The lower deck of this car has snacks and beverages.
There's a few things people should consider before taking a long distance train. It's definitely not faster than flying (duh), it's likely not cheaper (definitely not in a roomette) and it's possible and not unlikely to be delayed. I've seen people's first train experience completely sour because they were unprepared for a delay, vowing to never return.
You basically need to consider the time on the train part of the vacation and overall experience and not just a means from A to B. That's pretty easy for me in a roomette with great views.
If you've made it this far: the California Zephyr is my favorite route and I would say the consensus most beautiful route. Chicago to Denver across Iowa and Nebraska isn't so great, but from Denver to San Francisco (well, Emeryville) is fantastic through the Rockies and Sierra Nevadas. Mountain passes, switchbacks, long tunnels, Donner Lake, etc.
Accordingly, if you just want to dip your toes in, the best way to do it would be to fly to Denver, then train to San Francisco and fly home from there. It leaves Denver early in the morning and you get to SF the next afternoon.