I've just setup a new domain and have created two Windows 2008 R2 domain controllers. The first DC has all the FSMO roles assigned to it by default. I have been told that it is best to distribute the FSMO roles between the two DCs. I plan to make both DCs GC servers, as well.

I know how to technically reassign the FSMO roles but wanted to get some advice as to what FSMO roles would be best to assign to each of the two DCs.  Any a

Hi

 I always prefer that all fsmo roles on a DC and it is be a physcial server.(cause if need to bare metal restore to dc).Also for redundancy each dc's has GC role.

 And these two DC's configured with AD DS and DNS roles,And also you should check this ms official "AD DS Design Guide"

https://technet.microsoft.com/en-us/library/cc754678%28v=ws.10%29.aspx?f=255&MSPPError=-2147217396

If it's just a directory with a few (two in your case) domain controllers, then have all FSMO roles on one DC is OK. If it's a complex environment, you might need to adjust the placement of FSMO roles according to your specific network environment.
 
Take a look at this KB article and see if it's helpful:
 
https://support.microsoft.com/en-us/kb/223346
 

Regards,

Eth