We leave May 3rd also - and we have a 5 year old son. We also have a 2 year old son. Where are you staying? We're at SSR until the 9th then AKV from the 9th -16th.
I'm more concerened about my 2 year old (Mr. Independent, wants to do everything by himself, doesn't like to hold hands). My 5 year old listens better and is used to the parks and large crowds (this will be his 4th trip). My biggest suggestion for the 5 year old is don't assume that because he doesn't use a stroller at home he won't want one in Disney. It is a lot of walking and May does get hot (mid-upper 80's). I made that mistake last when he was 4 and his brother was 1. I took a single stroller and he was a trooper, but really wanted to get in and take a break throughout the day.
We also have SafetyTats - temporary tatoos with my cell phone # on them just in case we get separated.
I'm also planning on having a general touring strategy, but also allowing my 5 year old to dictate the plan more. I remember last year in the rush of things he really wanted to ride The Great Movie Ride one more time. I kept saying - lets see if we have time after we do some of the other things we haven't seen yet. We never made it back to the Great Movie Ride and he still talks about wanting to ride it again. This year - if he wants to ride something again - we will ride again (as long as the wait isn't outrageous).
33 days and counting! Have a great trip!!