This paper explores expressiveness of asynchronous multiparty sessions. We model the behaviours of
endpoint implementations in several ways: (i) by the existence of different buffers and queues used to
store messages exchanged asynchronously, (ii) by the ability for an endpoint to lightly reconfigure his
behaviour at runtime (flexibility), (iii) by the presence of explicit parallelism or interruptions (exceptional
actions) in endpoint behaviour. For a given protocol we define several denotations, based on traces of
events, corresponding to the different implementations and compare them.