Plitvice entrance advice

Note that you can buy a 2 day ticket which is less than 2 1-day tickets.

I'm not sure it matters that much if you are planning to spend 2 half days
there. Unless you want to walk every inch of the park, whichever entrance
you go in, you could use the boat that goes across Kozjak Lake (P2 <-> P1)
to go from one entrance area to the other. I say "area" because whichever
entrance you go into, you still have a descent down to the level of the
walkways.

I believe that your 1-day ticket allows you to use that boat once, in either
direction, so use it wisely.

There are buses that go between P1, P2, and P3.

Note that the caves and stairs/climbs are closed as of right now, probably will
still be that way in a month. The walkway that takes you close to the base of
Veliki Slap was being reconstructed in the spring.

I haven't confirmed this, but other info on the forum indicates that if you stay
at one of the in-park hotels, they will validate your 1-day ticket for a 2nd day.

This is a good map to give you the complete view of what's available:
Park Map

I visited Plitvice this spring. We stayed at the hotel next to entrance 2 (or B) and hit the entrance at 8 AM. Took the tram up to the top of the Upper Falls, hiked down to the boat ramp. Took the boat across the lake, had coffee and a snack and then hiked the Lower Falls. We were done by noon. We had the Upper Falls almost to ourselves and it was devine.

Thanks so much for your response- it is very helpful. We are looking forward to see the park!