We don't have hopper passes, so one park per day is fine with us
We are planning on staying at one of the value resorts.
You made a great choice to stay on Disney property. You can take the free buses to the 4 theme parks, 2 water parks, and DTD. Each theme park has its own bus. The buses will be marked when they arrive at your resort bus depot.
If you bring a car, parking is free at your resort. Parking is also free for you at the parks and DTD. Just show the theme park parking attendent your parking pass, which you keep on your dashboard in front of the steering wheel.
It is faster, when visiting Magic Kingdom, to take the bus, not drive to the parking lot. The car lot is on the other side of a large lake, and in addition to parking your car, you have to take a ferry boat or the monorail to the other side of the lake, to reach the park entrance. However, if you take the bus, the bus depot is right next to the park entrance. Lots of people like to park at the MK lot and take the monorail or ferry to MK. It's fun. Just that it takes a little additional time.
Some places you will see boats. In front of MK, at the Epcot World Showcase, and just outside Epcot International Gate, between France and the UK. You can board any of these boats for free. The boat just outside the Epcot International Gate will take you to the deluxe resorts on Crescent Lake and also take you to Disney Hollywood Studios.
You are also allowed to ride the monorail free. One monorail circles around the monorail resorts. One monorail is an express from the TTC (MK parking lot) to MK and back. The last monorail goes from the TTC to Epcot and back. Even if you ride the monorail to just look around, plenty of people do that. Stop in at one of the beautiful monorail resorts and take it all in or have a meal there.
Disney doesn't want people exploring too much on foot. There's critters, and there's lots of cars. The Florida sun, heat and humidity will defeat many people after just a short walk. You can walk all around your resort, and all around the parks, but if you don't see a sidewalk, don't walk there.