Healthy bank of miles, could fly UC if ya wanted.
It all comes down to what you want to spend on the holiday and if you want to earn some miles to keep on travelling or cash out so to speak.

With the Economy M fares you will earn flex eco miles and TP, whereas with straight out reward fares you would earn nothing and still be spending money on the taxes and surcharges - which can make up a large amount of the cost anyway.
Eco - PE is a tricky one, upgradeable economy classes have sometimes been known to be more expensive than the discounted PE in the first place, so you are paying more and sacrificing miles for less of a reason. My advice is to set your dates and then do a search on how much the PE seats are showing at straight cash value.
If i were you though I would be looking at buying an upgradeable Economy ticket and then going into UC for the journey - surely brownie points with the misses and a hell of a way to start and end a vacation.
I do like these kind of mileage puzzles so please do post again if ya need any help 8D