Our Personalized Touring Plan software supports only a single park and single date per plan.
Although the methodologies we could could theoretically apply over multiple parks and days, the mathematical computations involved quickly become overwhelming, and it is not possible for us to optimize such plans in a reasonable amount of time.
Perhaps in the future we will allow you to combine nearby parks (like Disneyland and Disney California Adventure or Universal Studios Florida and Universal's Islands of Adventure) into a single plan. We also think it'd be great for you to tell us the attractions you want to do over your full multi-day vacation and then have our software calculate where and when you should go on each day. However, neither of these options will be available any time soon.
For now, your best option is to create one "plan" in our system for each park you plan to visit during a day. For example, if you are visiting two parks, create one plan for the first half of the day and a second plan for the second half of the day. Combined, these effectively give you a full day of touring.
We offer some multi-day Premium Touring Plans that do this, including 2-day, 2-park plans for Universal Orlando (which is actually 4 individual plans). If you are copying and customizing these plans, be sure to adjust the individual plan hours to reflect how long you plan to spend in each park on each day.