Maybe lots of small canvas photos showing screenshots of the old Monzo logo/early design iterations, I think I’ve seen a super old one on Instagram… link or Link . Maybe some plants too (fake) they always brighten up a room. Not sure what ones though.
I still like my original idea of a blown up version of @kieranmch blueprint Monzo logo, maybe with lots of the old prepaid cards that @HughWells has to form a boarder.
Not too sure about the table, again though maybe some of the old prepaid cards could be turned into some coasters? 
A bowl full of random stress balls could be interesting.
A few of these would be a good idea too: Hot Chip 3D Print Orders
Personally I think you should go retro with a blackboard, sticker wise I’m not too sure… Maybe fridge magnets relating to some Landmarks where your offices in Cardiff, London and Vegas are located. These stick to white boards don’t they?