Ideally run HSRP on the routers and have them DHCP relay to something that does redundant DHCP well (infoblox, ISC DHCPd etc). As expressed routers doen't do DHCP robustly.

Cisco supports HSRP on the 3560 but not VRRP? I'm getting about 45 seconds to failover from hardware loss, and 45 seconds again to fail back when the higher-IP unit comes back online.