What about carbs to replenish the glycogen you've spent during your workout? The grapefruit drink and fruit are a start but it seems your focus is on the amino acids and protein. Aerobic exercise is fueled primarily by glycogen, especially at SST, Threshold and race pace intensities. Protein is good and necessary, but secondary to carbs when it comes to fueling cycling for both the ride and the recovery. Check out this link, especially the importance of replenishing glycogen stores right after the ride and how carbs dominate and protein is secondary:
http://www.carbboom.com/education/recovery.php
Sure these guys are selling a product, but do a search on "critical half hour glycogen" or something like that and you'll find plenty of studies referencing the need to keep your glycogen stores topped up for aerobic training and racing. A lot of folks, especially those coming from weight lifting put too much emphasis on protein and neglect the importance of carbs/glycogen for endurance sports. This quote from "Advanced Sports Nutrition" by Dan Bernadot says it really nicely:-Dave
P.S. you've hit on one of the best things about power meters in your post. They give you an objective yardstick for measuring performance gains independant of how other riders are doing. Your speed could go up or down on any given ride depending on terrain and weather but if your power steadily increases you really know the process is working. That's a big reason to not only ride with a PM, but to load and store the files for review and later comparison. It's really motivating and once you get enough PM ride history to get good data from the Performance Manager in CyclingPeaks WKO+(the best PM analysis software and well worth the price for this feature alone) you can really understand your training and peaking cycles.