We have not stayed on the Il D'Oleron and only spent a day touring round but based on that admittedly brief visit we very much prefer Ile de Re and have returned there 9 times. Both islands have their fans but we found it much more commercialized and busy than Re and this may be due to the removal of tolls from the Oleron bridge. The tolls are still charged on the Re bridge but at a reduced rate now that the bridge is paid for and this has been justified by the authorities as "Not wanting to go the same way as Oleron"