We are a family of 5, kids ages 7, 5 and 4. We have one day in each park, MNSSHP and then one “bonus day” b/c we bought UT tix during a special where we got 4 base tickets plus one free (so no PH).
Going last week of Oct/First of Nov.
Question: Which park would you choose for your “bonus” day?
We will have MK for a full day and for the party so feeling like I should choose between the other 3. WWYD??
I would think with kids that young you should do two days at MK I think there is more for kids in MK. You can do HS in a day or less. AK can be done in a day but a long day. So that leaves Epcot I like at least two days for Epcot but it is my favorite park. So all in all you have 6 park days. I would do whatever park you decide the day after MNSSHP because the kids will most likely be too tired to RD and you would have done most of the park already on your first visit. What I would not do is to do Mk and MNSSHP and count that as one day if so you would probably need to go back to MK.
Last year, I did 2 MK days and 1 at each other park. I really felt that I needed more time at Epcot. BUT, I am an adult, so your kids might think differently. HS is still kind of shortish, while AK is I feel a park where you can take your time to enjoy more time.
FPP are difficult to snatch at AK. Maybe plan for another day at AK, but while you are are on vacation, if your kids say I REALLY want to go again to EP or HS, then you can change to the other park.
this is good, we are being flexible to make a game time decision. 
mom and dad would prefer another day at Epcot esp during F&W! Really wishing we had purchased PH.
this makes sense, Ive been thinking 2 MK days. But we are all Star Wars and Toy Story fans, but unsure that there is enough for two days there even with our fandom
I believe you might be able to add park hopper once your there.
We arrived at RD last year. Without TSL last year, we ended doing: TSM x2, ToT, RnR, ST, Muppets, Little Mermaid Show, Beauty and the Beast, Fantasmic, 1.5 hour lunch at Hollywood Brown Derby, met some Star Wars characters, met StarLord and Baby Groot, Walk with Disney and took a 4hour break at POR.
My sister arrived around 11am. They did Beauty and the Beast show, ST, TSM, TOT, met some Star Wars character, lunch with us, Frozen Sing-a-Long, Fantasmic, Little Mermaid Show, Muppets and had free time to go shopping. We also took a picture with Flash McQueen.
I think one day would be a lot at HS.
This helps a ton! Thank you!