Hi Chris!
The water parks are one of my family's favorite places to visit at Walt Disney World. Since we live so close, we often just take a day trip to take advantage of the water on a hot day. We are very familiar with the toddler area at Typhoon Lagoon and Blizzard Beach. They are both really great for kids, especially a 2 1/2 year old. My son is 3 and loves the slides and sprayers. Typhoon Lagoon's
Ketchakiddee Creek is more confined than Blizzard Beach's
Tike's Peak. You will find that the seating area is smaller at Typhoon Lagoon. I hate to tell anyone to rush when at Disney, but if this is where you think you will spend most of your time, then head there first to stake out your chairs. We usually plant our things somewhere quiet and then visit the toddler area throughout the day.
Split up. Get to the park when it opens, have one of the adults enter first and go straight to the toddler area at your desired park. Take a few of your belongings with you so you can claim some chairs. Have the other adult and child meet you there at their pace. I know 2 year old's tend to walk a little slower, especially when there are so many cool things to see. If you are interested in renting lockers or towels, do this after you have secured a place for the day.
Tike's Peak at Blizzard Beach is more spread out, therefore there are more areas with chairs and coverings. Even though this section is larger, you still want to get there fairly early.
If you end up somewhere else, just remember that the toddler areas are just a lazy river ride away.
Have a magical day!
Leslie