As others have pointed out there is an important distinction between reputation for a node and XP. I vote on AM nodes if I think they are deserving of an up vote. It's possible I less often down vote AM nodes because some of the reasons I might down vote a node don't apply to AM (to signal to the OP that I object to particuarly bad formatting for example).

I find that the number of votes I have to "spend" is not generally an issue. Some days I rip through them and am dissapointed at the end of the day that I need to wait a couple of hours before I vote on a few deserving nodes. Other days I find I've only spent a few votes.

Really deserving nodes don't go away. Bookmark them in your Personal Nodelet for voting when the vote tide comes in tomorrow. Good nodes are worth re-reading in any case and the bookmarking works quite nicely now (if I may say so myself :)).

One thing that I would like to see would be the ability to case a null vote on a node so that you can then see the node's rep. The null vote wouldn't adjust rep or XP, would cost one vote and would disallow further votes by the caster on that node.

If a node gets high rep, it is allready possible to see what its rep is - look at Best Nodes. There is value in voting AM nodes and, if its a good node, Am can see that it is good.