Crowds usually very manageable. As others posted, weather is hit or miss, somedays are pool days, some are not. The temps can be across the board!
I am expecting with the opening of BOG, MK will be definitely a little more crowded, but overall we completing what you want to do early in the day is best. We have see E ticket rides upwards to 120 minute waits and then other days walk on over and over again. It really isn't a true science at this time of year. For the most part, picking the best parks on their best days, you will have no issues whatsoever doing what you need/want to do.
I don't know how big an impact BOG/FLE will make, but I would expect there are diehard WDW fans like ourselves making the trip to enjoy the new FLE.
Kelly