Yes, I think hitting FL first is a great strategy with younger kids.
Of the rides at DL, the most “adult” ones are (roughly in order) Matterhorn, Space Mountain, Indiana Jones, Big Thunder Mountain, Splash Mountain, and to a lesser extent, Star Tours and MFSR. RotR is really tame but has a height requirement.
It should work fine, though honestly I usually use the TP as a rough guide of what I want to do. Try to chip away at the LL rides in order of which is most in demand, but use the two hours in the morning when crowds are low to ride as much of those as possible and then you can get a LL for them later as well. Here is the rough order of priority that I give in the pinned Genie DL thread:
- DL: IJ > Space > HM * > MFSR > Splash * > Matterhorn > ST > BTMRR > iasw * > other
- DCA: WS > Gotg * > TSMM > Soarin > Incredicoaster > GRR * > Monsters > Goofy
*Priority may vary due to heat/weather (Splash, GRR) or holiday overlay (HM, iasw, GotG).
I have always found hitting JC early in the day to be a good strategy, because that line sucks. Otherwise, as I said above, try to knock out the highest priority LL attractions.
I like your plan. You should have plenty of time to get everything done in three days. Your DCA day will be critical since you only have one day and the lines there can get super long. I would plan to get ILL for RSR. Everything else is pretty easy to get on LL or SB if you plan it out right.