..and from an operational perspective, GLBP works relatively
Any suggestion as to what IGP protocol is best for this scenario?
This is more of a cisco-nsp question, but probably OSPF, as it's
supported by the routing daemons on most *NIXes out of the box. I
don't know about Windows.
Are you doing anycasting or something?
If simple redundancy in the default gateway is the goal, another (and
probably simpler) method is to implement HSRP or GLBP between your
routers which are serving the hosts in question.