Yes it costs more booking a hotel for a couple of nights, but it’s still probably going to be cheaper than upgrading to business class. You usually have to book it directly through their website (look for “multi city”) rather than through an agent.
I've never really had much luck.
Same boats for me exactly. My solution is just to get up and hang out in the aisle, or near the emergency exits whenever I feel like it. Sometimes I read standing up, I stretch, I even sit on the floor with my legs straight. I'm polite to the staff and other passengers, and I have never once had anyone tell me to stop what I'm doing.
It's great in the middle of the night when everyone else is asleep. An hour of stretching makes a BIG difference on those 14 hour back-to-back flights.
I'm over 6' tall. I've flown multiple different lie-flat products on long-haul flights (and will try out another one next month), and I've never been on one that was too small. I suspect because that type of premium-cabin seating is built with assumptions about the demographics of the customers (in other words, they assume the typical passenger in these seats will be male, and aim to support a range of typical male sizes).
What you're paying for in business class is the privilege of having a flat bed or a big comfy chair, on demand.
I get that they have to cramp in as many seats into a plane as they can in order to get the prices down to a point where normal people are willing to pay for a ticket. But it's really such a pain in the butt.
Would I pay double the price for a ticket to get a bed? Probably not: long distance flights are already expensive. And knowing how everything on planes is smaller than in real-life, I'm sure whatever they'd sell me as "a bed" would not really be accommodating either.
As a consequence, I now just avoid these long distance trips. A pity for one who loves to travel but on the upside, it's better for the environment anyway.