Clustering provides quick failover, usually under one minute. With no changes for DNS (you connect to a virtual machine name, not a NetBIOS Server Name. Clustering also takes over all jobs/ logins, DTS packages, and is very low for administrative overhead.

If a cluster fail's over, there is not much that needs to be done (except examine what happened). Many times I have found that a cluster has failed over, and no one even knew it (yes, that means that the monitoring solution needs tweaking).

The most common solution these days is a cluster in your primary datacenter with log-shipping or mirroring to the backup data center.

I would also echo the comment that with as many databases that you have, clustering will be a breaze versus setting up the other solutions, but clustering won't protect you for losing for first DC (geographically dispersed clustering will, but that's a whole different animal)