H.P.
We have been going to GWL in the Poconos twice a year for the past 4 years. The first time we went, my twins were 18 months old and my daughter was almost 4. It was hard the first time b/c my twins didn't want to go in their pack n plays (they had never slept outside of their cribs before) so we didn't get much sleep. Obviously, now that they are 5, it was much easier when we went a few weeks ago.
They have fairly large refrigerators in the room so bring some food and snacks for your kids. Milk for night time (or take some from the dining room and put it in your fridge if your two year old likes milk.
They provide towels in the water park, but definitely bring a robe or some sort of beach cover up so that when you leave the 86 degree water park and head back to your room, you're not freezing. When my kids were little, I also had them wear water shoes (or crocs). They have a croc store right outside the water park now, so that's good.
The water park has life vests for the kids, but not sure if they have tiny ones for a one year old. Most likely, you'll be holding him/her so no need. But there will be small life vests for your 2 year old.
There is a Starbucks there and if your kids are early risers like mine, that could be good!!! They might also like the kids' craft and playroom area. Bring some cozy pajamas because there is a show and story time at 8:00 pm. It gets crowded but maybe your 2 year old would like it.
Outlet shops are 1/2 mile down the road... check it out on your way there or way home. Good deals on Carter's, Stride Rite Sneakers, Nike, Ralph Lauren, Ann Taylor etc...
Oh, one other thing, you can get into the water park at 1:00 the day you arrive but your room might not be ready until 4:00. They will text you on your cell phone when the room is available. We packed a day bag with bathing suits. I actually would recommend changing in the lobby bathroom rather than the pool bathroom b/c the pool bathroom is all wet and yucky. Easier to change kids were it is dry. Lobby bathroom is right near check in area.
The buffet is decent but expensive. Little kids might be free, though (or heavily discounted). We sometimes order pizza from the pizza hut in the pool level. It can be delivered to the room if your kids are too tired to eat in the buffet area.
The arcade is a lot of fun too, but maybe your kids are too young... you'll have to see when you get there... lots of flashing lights and noises.
Have fun!!!