I did a lot of reading about acclimatization last summer after having problems in Wyoming's Wind Rivers. While I had studied about altitude illness in a WFA class, I'd never experienced it because I grew up in Wyoming and Colorado and never had any problems. However, I've lived at or near sea level most of the time since and done most of my backpacking in the Cascades at altitudes of 5,000 to 6,000 feet. I didn't develop any severe symptoms, but it sure slowed me down!
It appears that you didn't adhere to the two rules of acclimatization: Climb high, sleep low for several days, or don't raise the altitude of your sleeping place more than 1,000 feet per day.
For your first trip, you basically went straight from sea level to 14,000 feet.
For your most recent trip, you did the right thing the first few days (climb high, sleep low), but then you raised the altitude of your sleeping place by 7,000 feet. Altitude sickness is more apt to show up while you're sleeping.
In your shoes, I would plan the trip around the acclimatization criteria: two-three days of climb high (10,000-11,000 ft.), sleep low (maybe sleeping higher than Denver the second night, at 7,000-8,000 feet). After that I'd start camping at an altitude a bit lower than the one to which I was climbing (maybe 8,500-9,000 feet) and try not to raise the altitude of my sleeping place more than about 1,000-1,500 feet per night. That's what I'm planning when I go back to the Winds this summer.
You might want to hold off on climbing 14ers until near the end of your trip.
If you still get AMS symptoms with such a regimen, then it may be time to try a preventive diamox program. However, you might want to talk to your physician now and take some with you in case you do develop AMS (but take it at the very first symptoms--Jeff's story demonstrates that you shouldn't wait until you're really miserable).
I personally would not try to substitute drugs for a proper acclimatization program. Your mileage may vary, though, especially if your vacation time is very limited.