Hi, Bridget!
So happy that you enjoyed your stay at Disney's Art of Animation Resort!
Regarding your timing for your next trip, the first thing you need to consider is this: temperature. While weather patterns have been known to surprise Guests of WDW throughout the years, you are more likely to have a warmer stay in early June than in late March. Water parks and water attractions such as Kali River Rapids may not be enticing, depending on the weather, either. Of course, the day we left WDW, the temperatures rose to the mid-70s, so it really is hit-or-miss that time of year. I've also brought hundreds of high school seniors to WDW throughout March and early-to-mid April and have found some days to be in the 70s or 80s throughout the trip. In short? If traveling to WDW in lat March, come prepared for cool mornings and evenings with warm days in between. You'll be able to enjoy
Epcot's International Flower & Garden Festival should you head to WDW at the end of March, too!
Early June will likely bring Disney's Hollywood Studios'
Star Wars Weekends. Ever-popular, these weekends are a special treat for Star Wars fans. Weather is typically in the 70s and 80s. Crowd levels at Disney's Hollywood Studios will be high on those weekends, though, so avoid that park if Star Wars is not your thing.
Price-wise? I did a quick room search for each of your selections and found that a room at AoA (in a Little Mermaid Standard Room) is only 1-3 dollars different most nights. Enter some dates into the tab "Room Rates" and you'll be able to compare the cost of your stay during both of these weeks.
Happy planning, Bridget! Send more questions as you think of them; we love to help!