Thanks for the advice - even though I sort of took over the OP thread - I think the advice applies to him to.
Because of the thread title there will be dozens of people reading this thread. Because of your knowledge of WDW, & because of your style of planning, you ask LOTS of good questions. When we answer, we're answering not only for you, but for folks who hadn't thought to ask.
So, a couple of points you bring up that I wanted to talk about:
- The Nemo Subs - most of the stuff I've read on this is its
very slow loading and builds long lines, though perhaps a lot of that was when it first opened. Are you saying the lines are shorter now? You might consider it boring about I have great childhood memories of 20,000 Leagues at WDW and the idea of getting to show my DD and DW this ride, even though I know it's not the same, but the closest we'll ever get, makes it very high on my list.
The lines are nowhere what they were when it opened. But it remains a slow loader & a relatively long ride. If you were on the first boat, you'd still kill 35 min. minimum. Which is why i recommend not riding it first thing...(especially if you only have 3 days....& probably only 2 early mornings at DL). But then again, i admit I'm not a fan.
I'm a believer in HGs "rules"....i follow them....we agree on 95% of all things DLR. But Nemo is one of those we agree to disagree on. 
- FL / MM ride order. You mention this...where do I find it? I guess I assumed like MK, you hit Dumbo first, then Peter Pan and go from there. In brief, we arrive on Saturday evening, and Sunday is our first day. I figure being the weekend its best day to take advantage of MM hours, especially since as said before there's a good chance we'll be lying awake at 5 AM.
Peter Pan is first (always first) & be one of the first on. THEN Dumbo. & you know the rest. 
The best day is the earliest possible MM day. (for lots of reasons) & Sunday is a great day. 
In the summer I would recommend getting to Security at 6:20 for a MM 7am opening. (you can munch Bfast at the turnstile since you're one of the first couple in line).
- You mention the strategy of starting in DL and then moving over to DCA in the afternoon. I am not sure that this will be as good a strategy this summer as in the past. We will be getting there a mere 5 weeks after Carsland opens. I would expect to see a large surge in popularity of people visiting DCA versus previously, especially at times that are popular for AP holders. (With a million of them out there, they can't ALL be going the first week its open.) For that reason - my thought was to focus our first day (Sunday) on DL, especially since there is much more we are interested in seeing there. We will use the MM that day, and also take advantage of FPs of course. (I typically have 4-5 sets of FPs in my pocket by noon at WDW, and that's with park opening at 9 AM, so I expect to have a full load of DL FPs by the time I start using them.) I will keep in mind if the park starts getting overly crowded that we could
swing across the street for a bit.
You're right. Carsland will likely change everything. The 3 things that will affect touring strategies most will be the new hours of DCA, the MM being offered & the AP offerings. Once these items are KNOWN, the strategies of those who post often here will be Conventional Wisdom within a week.
But it won't change the big picture strategy of getting to one of the parks early (every day), & possibly hopping when THAT park gets to crowded. I'm guessing that for the 3 day visitor you'll want to start 2 days in DL & one day early at DCA.....but it might be 2 days in DCA & one day at DL. But we won't know for sure until the hours/MM & AP confirmations are known....& might not know until Carsland actually opens up.
- We would then on Monday hit Carsland first thing and work DCA from there, as well as do WoC that night. I suppose we could hop over to DL later that day if necessary.
-I find it interesting you tell me that I shouldn't say I don't need to plan as much at DL, but also that I am overthinking it. Which should I do? Honestly, I pretty much work it by having a strategy for the first few hours of the day, and then remain flexible with the goal of getting FPs whenever I can. (Gonna miss that strategy at WDW going forward.) I would very much appreciate that Fantasyland ride order!
I asked questions here & was skeptical of what this Hydro-dude & 6-10 others was trying to tell me. By the second day of my first visit I "got it". The DLR strategies are a little different than the WDW strategies
.... & be prepared to zig when others are zagging (which might include "hopping" once (or maybe twice) a day. Being "productive" imo includes picking up the 3-5 FPs early that you intend to use in the evening when it's crowded.
. I must say now that our little boys are grown men we do spend a few days getting up later and staying at the parks later knowing the lines will be longer...
