This is a late post, neither of the two major roof rack vendors Thule or Yakima have roof rack solutions for bare roofed Odysseys.
Having the OEM/"factory" (dealer or self installed) roof rails is a great starting point, but I strongly recommend going with aftermarket cross/load bars from either Thule or Yakima. With the aftermarket bars you have tremendous flexibility in the spread between the bars as well as the location of the bars. Have used the traditional Thule square bars for a couple decades with our Odysseys (starting with 1999, then 2006 and now 2015) with the Thule 415 then 450 crossroads feet (both discontinued). With stuff on the square bars like a roof box, kayaks or paddleboards its not too noisy. With just the cross bars the turbulent airflow howling is pretty annoying when driving faster than 25 mph.
Recently found a set of Yakima Jetstream crossbars at a yard sale and bought a set of Yakima Timberline Towers off a ubiquitous online auction site and installed them on the van. There is some airflow sounds but very subtle and completely acceptable even on the freeway--the Thule square bars will be put out to pasture.