We traveled to WDW twice last summer with our younger son (3 at the time) who pumps.
My best advice is to get a good touring plan (like Tour Guide Mike - my personal favorite!) - and arrive at the parks at opening time. You will be in the cooler part of the day and with fewer people you can get A LOT done. Then have lunch where it is cool and go on back to the hotel for rest and swim time - back to the parks at night for dinner and more fun.
We had some challenges with William's numbers - in particular we just toured the parks 2 days in July but one day he ran low ALL day - we could hardly keep him up. The next day was the opposite - he ran over 300 much of the day. (We did end up changing the reservoir in the pump in case it was the heat). Our May trip wasn't quite so up and down and I'm not sure why! If it was the heat or what.
I don't know the ages of your kids but with 2 who are diabetic on pumps, especially if they are young, you might want to ask for a Guest Assistance Card at Guest Services. You can tell them your kids are diabetic, etc. and staying out of the heat would be important for them - to keep their sugar stable and their insulin cool. Mostly they want to know what accomodations would be helpful rather than the diagnosis. I can imagine with 2 kids you could end up having one do fine while the other is low or high. It seems we often had to stop and treat highs and lows on the 2nd trip and that is when the GAC was most helpful.
There is also a "Frio" cool pack that is made for pumpers. I don't have one for William because he wears the pump in a pocket on the back of his undershirt so it wouldn't work for him. You can find them here:
http://coolerconcept.com/pages/inspumpwallet.htm I've not ordered them from there but this company does sell their products at the Children With Diabetes conferences (which are sometimes held at WDW by the way!).
I also suggest carrying enough supplies in case of emergency - like if one of the pumps fails. I carry a ton of syringes, lantus, humalog, etc. I also carry extra meters and strips and all the pump supplies. I keep that stuff in the room of course - not carrying to the parks!
I've found that using "Skin-tac" helps keep his site on really well when he swims. You need to use something to help you get the site off if you use it though - like Unisolve. We have an Animas pump which is supposedly waterproof but I still take it off in the pool. We usually leave it in the room but sometimes I have taken it with me to the pool. That is hard to do as you can't really just leave it unattended! He still goes in the baby pool so it is easy for me to sit nearby with the pump in a cooler case while he plays.
I never took a bottle of insulin the the parks but if the weather is really hot you might want to try that. William is so afraid of shots now that I really try to avoid giving a shot - I'd rather change out his reservoir and site which he tolerates much better. I usually do carry all the stuff with me to do a site change. Glucose tabs work best for us when he goes low but do carry whatever works well for your kids!
Congrats on pumping! Feel free to PM or ask here with any questions. We really love pumping - William has been on a pump since he was 2 yrs old (about 6 months after diagnosis) and he just turned 4 about 2 months ago.
(TEN, Count them TEN days at WL). This will be our first trip to the world since my oldest DD was diagnosed, youngest DD diagnosed in 2001. On top of that we will be traveling with them on insulin pumps for about two months. My main concern is the heat in June and the effect on the insulin in the pump. Before with shots we keep the insulin at First Aid to keep it cool. What experiences have pumpers had at Disney during the summer months and what suggestions do you have? Thanks in advance because the people on this board are the BEST!!! 
