One silver lining to the bus being packed is standing with one foot on either side of the articulation pivot. Feeling your stance change under you while you're standing still is neat.

My college years did not include all that many hangovers, but I distinctly remember not enjoying this effect one morning.

The trains around Munich, Germany were fantastic for that effect. 15+ cars long with wide, open pivots.

Boarding times though? I agree of course about the cool factor and I was sure to ride one when visiting London, but afaik the slower (dis)embarking times are why double-decked trains are primarily used on intercity trains and not on commuter/local trains or light rail (metro etc.). Typical busses stopping every two minutes are probably similar

Edit: wait, I know one in Germany as well. It's expensive but between Frankfurt airport and another major city, there is a rail line but somehow the bus is significantly faster and they're using double deckers. The front row at the top was, n=3, always free for me (all four seats) so you get a quite unique experience, at least so far as my bus experiences in mainland western Europe go :)