OK, I made progress since I first posted this. What I found is that after running the server with the AotBT mod pack, I could then switch it to MCPC+/Cauldron (one of the base options) and the plugins now load. Essentials and Lockette seem to be working fine (I haven't tested every command though) but I can't get Grief Prevention to work. It is loaded, and when I place my first chest, it sets the initial claim, however I cannot change the claim or add additional ones. When I select a golden spade, I get the message as usual about claim blocks and such, however I can't change the claims as it doesn't seem to be recognizing the right-click. Similarly the Stick inspect feature doesn't work, even within my own claim.
I *suspect* that the issue is a version incompatibility and that I need to go back and get an older version of Grief Prevention, however while you can get to older versions, there are none that are clearly flagged for Mine Craft 1.6.4 - the versions seem to jump from 1.5.1 (7.7) to 1.7.9 (8.0). If anyone else is running a similar setup, can you tell me which version of Grief Prevention you are running, and if you had to do anything special to make things work.
Here is where I found the file versions.
http://dev.bukkit.org/bukkit-plugins/grief-prevention/files/
Thanks in advance for any advice or help.