peer/transit circuits

[ning.shi () bell ca]

Hi folks,
I am looking for some advice on how to place the peer/transit circuits on the edge routers. Would like to find the best 
practice that would provide enough diversity without having an operation nightmare. e.g. putting peer and transit 
circuits on different routers will make the routing policy easier since peer and transit will have different policies. 
however, if I lost the transit router then all transit is gone. 

Any advice/reference would be appreciated.

Regards,
-ns