Congrats on starting a training journal and excited to follow along your journey!
I'd say it depends on how you want to approach the April 22nd 10 miler. If it's an "A" type event, then I'd probably shoot for the May 19th HM. But if you use the April 22nd 10 miler as a training run, then you might get a better performance out of the May 6th HM. In addition to the elevation changes, I'd look at the historical weather on those dates in those areas for the last 5 years. Even a week or two can make a dramatic difference in expected weather conditions. I use weather underground for historical temperature and dew points for different time of day.