Any receiver that has WiFi and 'Zone' capabilities will meet your needs for speaker selection and media streaming. Since you mentioned iPod, look for AirPlay ready to make the streaming part a hassle free setup. On Zone capabilities, specifically confirm if streaming media can be routed to Zone 2.
There is a notional belief that Onkyo's are on the lower side of reliable. Thought all receivers should be well ventilated, there is some anecdotal correlation between setting up an Onkyo with insufficient ventilation and high failure rate (more than other receivers setup without adequate ventilation).