Do I need AD Sites & Services with only 2 DC's & 6 Sites with multiple subnets?

Hi Guru's,

I am setting up a new AD infrastructure, which will consist of 2 Domain Controllers, file server, exchange server located at the one site, and then I will have 5 other sites which will house no domain controllers or any other servers for the time being! Each site will have around 5 different subnets one for the LAN, Wireless (Guest), Wireless(Corporate), Wireless(Workshop), Phones)

Do I need to configure sites and service in the initially? Considering I wont really be needing the replication control for DC's on other sites, or should I still configure it for the multiple subnets that I am using in each site so they can be easily identified and linked to a site in AD?
 
I was thinking I would put it in anyway, as it will create the ground work for any future expansion and additional DC's if and when required, but wanted to get the hardcore pro's opinions on that, and hopefully let me know if there is anything I am not considering, missed and or reasons other than domain controller replication why having sites & services configured would be beneficial.

Many thanks in advance