A couple of other ideas just to make things more complex!
The kind of ticket you get can depend on whether you will ever return again in the future.
For example we have the Disney 'Magic Your Way' 10 day pass that has hopper/non expiry facility, with 4 days Water Parks included.
Chose that one because we do not visit WDW excessively and so far we have had 2 holidays and still have 4 theme park days plus 2 WP left.
Just find it works best for us, not everyone's idea of the best way to do things. You don't have to get the 10 one, they do 7 days etc too....
Personally I wouldn't go for the Flex ticket, whilst I have used them before and it gives you good access to 4 parks would you really get value for money from them? You have 14 days Disney tickets plus 14 days Universal/Sea World too, that's a lot to cram into 2 weeks.
Universal/Sea World often have offers on, SW recently had one where you could get 7 days access for the price of a 1 day ticket ( we had these last August and were incredible value for money), often US have a 'buy a 2 day ticket get an extra day free' type of thing on.
We have (had!) Universal Annual passes (they actually expire very soon) at $179 cost less than the Flex ticket, and whilst you don't get Sea World access you get a host of benefits including free car parking (quite a saving as it's $10 or so a day now), plus merchandise/restaurant discounts etc
They can also work out excellent value for money as the renewal price is just $99, naturally to make full use you have to find a good reason to go next year too!
Sorry if this sounds more hard work

, and I know I am getting carried away here but like I say do what's best for you - however, it's always good to have a different way of doing things.
We used
www.mapleleaftickets.com for our MYW one's