Why would you ignore Alexa only to a certain extent?
Seriously, it's really something to drop entirely from your priority list, it's no priority whatsoever, just the thought you spend on thinking what your Alexa ranking is would be a waste of time.
You need to look at your traffic logs, (You're using Google Analytics right?), that's what matters...seriously. Alexa has no influence on your Google analytics reports and those reports is the thing that matters.
Just do your thing, continue to build backlinks and content and forget the whole green PR bar.
If you do nothing that is out of line with Google's webmaster guidelines then it will all be good in the long run.
Only Google knows your true PageRank so don't rely on Toolbar pagerank results.
If you're not in the business of selling links then you just need to focus on building content, backlinks and analyzing your traffic logs, see what pages do well in obtaining traffic from the SERP's and try to hold on to that position or improve.
So please stop worrying about Google's update!
