To connect remote sites across Canada to a central location, would MPLS be good over the WAN and BGP in the remote sites?

Yes MPLS is ideal and most commonly paired with BGP for small, medium and large scale Enterprise Network Designs. Items to consider for each remote site being connected is equipment diversity ( dual routers ) ,-wan diversity ( dual carrier providers ) will insure no single points of failure or (spofs) exist insuring there is always a contingent path should a primary fail.

Yes MPLS is ideal and most commonly paired with BGP for small, medium and large scale Enterprise Network Designs. Items to consider for each remote site being connected is equipment diversity ( dual routers ) ,-wan diversity ( dual carrier providers ) will insure no single points of failure or (spofs) exist insuring there is always a contingent path should a primary fail.

I agree. MPLS is an excellent option. You can couple this with your own IPSec VPN as well. Your MPLS provider can also provide the connections for this as well.

One benefit of using MPLS is that you can specify CoS/QoS with your provider to get VoIP over WAN.