Here's an interesting read comparing professional inland and coastal/island observatory sites:
http://articles.adsabs.harvard.edu//...00003.000.html
It's not particularly relevant for this discussion given the global nature and altitudes involved, but I found the Conclusion amusing in this context: "The ideal observing site is a single, steep volcanic cone rising out of the ocean"! Not exactly the ideal retirement location...unless I can convince my wife to move to Hawaii
