The short answer is I am not sure yet.
I am intrigued by the Muslim hajj -- the pilgrimage every Muslim must make to Mecca at least once in their lifetime. Given that the Asherite religion is very loosely based on Islam, I wanted to include something similar. A mandatory religious pilgrimage is rife with adventure potential. Set routes get established, caravans set forth, bandits plague the caravans, political conflict ensues to guarantee (or possibly exploit) the pilgrim's passage, etc. I am sure there are lots of other possibilities I haven't even considered.
My idea is to have five sacred sites or cities in the Asherite faith, with the religion requiring each site recieive a visit by each believer. Ideally, one visits each site in the same journey -- a religious pilgrimage lasting a year or so of one's life. The five sites are the Crown of Stars, with five being a nice number represented by the points of your typical drawn star.
What those five sites are and why they are sacred I am still trying to figure out. I don't want to cleave too close to Islam or any other real religion, so I am wide open to any suggestions. Got some?