We have DS 3.5 and have made over 15 trips to DL since he was born. Hopefully by our trip on Memorial Day he will finally hit the 40 inch mark (he's about a half inch short at this point). But, my DH and I still love the big rides and hit them almost every trip. Here's how we do it ride by ride to make the most of FP, swapping and Single Rider lines:
Space: Get one FP for the first adult and then use Child Swap (get to go in the exit and ride almost immediately)
Splash: We rarely ride, but use Single Rider when I do (DH has NEVER been on the ride, which will change once DS can ride "How Do" as he calls it)
Indy: Single Rider (enter at the exit and bypass almost the entire line)
BTMRR: Get one FP for the first adult and then use Child Swap (functions like an extra FP most of the time, but every once in a while they will send you in the exit instead)
Matterhorn: If you have itty bitties (under 35 inches) or your kids are scared, the Matterhorn swap works very differently than the other rides. You all have to stand in line until you get to the Green Umbrella. Then you can get the Swap Pass for the second adult to use to enter through the ride exit.
Screamin': Use Single Rider when its available, but if the line is short enough that they aren't running Single, then just standby
Soarin': Get an FP. Then when you are ready to ride ask the CM whether Child Swap or Single Rider is going to be quicker. Swap acts as an extra FP.
ToT: DH usually skips this one, so I just use FP. You can get a Swap, which I am pretty sure works like an extra FP.
GRR: Never ride, so no idea how this one works. Can you tell we're not water ride people
Star Tours & Mullholland Madness (soon to be Goofy's Sky School): With both of these under major refurb/retheme it is unknown how they will work when they reopen.
Through judicious use of FP and getting only what we will actually need (typically only one per ride) we can hold FP for most rides that we want simultaneously. This frees up FP for Buzz (although it appears that is a thing of the past) and Autopia (my little one's new fave ride).