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.