FCIP is used to extend a SAN over distance and would usually be a better choice for replication between data centers. FCIP is where the fiber channel frame leaves the MDS on a gigabit Ethernet port, wrapped in a TCP/IP frame. The frame can be routed over the IP network and all the benefits of IP can be used. (QoS, fragmentation, compression, encryption). TCP is used as the transport to allow for windowing and guaranteed delivery and retransmit when needed.
FCoE fiber channel over ethernet is where the fibre channel frame is wrapped in an ethernet header and it is treated as a layer 2 packet by the switch. No IP routing capability on these frames.
Depending on the distance, and the WAN link between the sites, FCIP would be my recommendation. Another option if you need the bandwidth between locations is DWDM or CWDM. These solutions tend to be pricey.
Hope this helps,
Mike
