You are actually hitting at the perfect time. The 5th will be busy because it's the first day of the Holidays
(read more about them here)
But the rest of the week you should be golden as far as crowds. I would definitely recommend a day per park. Arrive before opening, which I believe during that time of year is 9 a.m. If there is a crowd, they'll let you in early. Make an immediate bee line for Potter (take a left at Green eggs and ham to avoid the longer trek around Seuss Landing). You will spend most of the day there between the lines for the attractions and shops. Then spend the rest of the day around the rest of the park. You may need Express later in the afternoon, but that time of year and in the middle of the week? Probably not. I would definitely recommend doing the queue for Forbidden Journey once, riding together probably the first time. After that, hit single riders. Travel as light as possible, not taking much in the way of bags as you'll have to stow them in a locker if you do...the lockers are free for rides they are required on (such as Forbidden Journey) but the line for the lockers get rather long.
Save butterbeer and any eating for after you have ridden FJ as many times as you want. You may experience upset tummys otherwise. The rest of the park just do it as you see it. I would recommend doing Jurassic Park then walking all the way around doing the other attractions until you get back to WWOHP. See it right before closing, all lit up. It's gorgeous.
The key to doing the Studios is to do the rides up front first. That means Rockit (if it's open) then Shrek, then Jimmy Neutron, then Mummy. Twister is usually walk on all day, and rides like Disaster, JAWS, and ET go quick. MIB has a great single riders line, but you will be split up, just like FJ. Turns whatever wait is listed to a walk on.
Around 4 or 5, they will have the Macy's Day parade which will feature Santa, and candy. Best seat is on the corner near Mummy and Twister. They do a tree lighting ceremony every night, and they will open the Christmas Village around 3 p.m.
I would say a day at each, then spend a third day going back between the two parks to do your favorites would be enough. The 4th day, go to Sea World. Great coasters, but the Christmas shows will only be on the weekend. So you may want to do it first, on that Sunday. Save Universal for the rest of the week. The crowds should be fairly light, except in Potter. During that time, expect Disney slow time crowds. 45 minute waits.
Hope this helps.