There is something decidedly unusual going on with these chests. Their contents are NOT fully reproducible using airplane mode. Except that if you follow the same path, you do get the same results. And it's not a predetermined sequence like the Tower spins, either. For example, if I start from the space 1W of the first Sweetest, go 1N (bunny), then 1W (200k gold). Whereas I can alternatively go back 1W (already claimed), then 1N (bunny, even though that chest was 200k on the last route!), then 1E (bunny). Or 1N (bunny) 1E (bunny) 1E (bunny) - three bunnies in a row instead of one being gold.
I haven't sussed out exactly what the variables are - for a while I thought it might be the direction you entered the square from, but I ended up disproving that. But I rather suspect that if you take each step in airplane mode, then
a) If it was a bunny, turn off airplane mode and do something else (e.g. Ancient World and back) to save. Turn airplane mode back on, take another step.
b) If it wasn't, quit, turn off airplane mode, restart, and pick a different square to buy next.
you can likely get every single chest you open to be a bunny. Which would make even 8 bunnies for 600 a bad deal, that's 75 per bunny and there are oodles of squares costing 70 or less.
Will update as I do more tests and learn more.
Update: OK, turns out to not be every chest. You can get most, but you do end up sometimes at a point where no chest you can pick turns out to be a bunny. Ended up at 10 bunnies from 11 moves after the first collection interval.
Further update: Yeah, seriously weird. I've currently gotten into a state where every chest of the same cost gives the same result, which wasn't the case before. There's obviously some rule here - it is a computer program after all - but I can't think what it might be!