tRIO is certainly the best client although others have their uses. For example, there is a modified Rioplay that works with Home Automation, this allows TTS to be sent to the RIO's.

The server is the harder decision, If you have a large collection then ARM will bomb out, jrec is a pain to install, i got stuck on an earlier version that tRio didn't work with. If your happy to use a web interface to make music selections, Streamsicle is very good but keep an eye on Slimserver as it may catch up.