As I've been reading up on how to migrate from ConfigMgr 2007 to 2012 (hint: there is no upgrade option), one common theme that keeps coming up is wether you need to use a Secondary Site to regional offices or just to use a Distribution Point. With ConfigMgr 2012, MS is trying to simplify the hierchy by requiring less site systems to do the same amount of work. A couple things to keep in mind when trying to decide between the two:
1) The Distribution Point role has been expanded on in ConfigMgr 2012 to do a lot more than in 2007, but it doesn't do everything!
2) Since Distribution Points does not include the Management Point role, you must take into account the extra bandwidth used by client systems when they connect with an MP in an associated Primary Site (or Secondary Site)
3) Same thing with the Software Update Point role, its checks will go up to the assigned Primary Site (or Secondary Site) to check for approved Updates
4) State Migration is not a part of the Distribution Point Role! If you plan on using USMT directly within ConfigMgr, this is something that you will have to consider
In the case of my envornment, I don't think the heiarchy is going to change very much, except for the introduction of a Central Administration Point and a 2nd Primary Site (right now I run a single Primary Site and 14 Secondary sites under ConfigMgr 2007).