Honestly I have a very small diaper carrier that I used in parks, it held 5 diapers, a carry wipe container and I could pack a non bulky outfit into it and it was no bigger than a formal evening bag. I loved it. Now that my kids are out of diapers I find I have to carry a backpack which is far more heavy than a diaper bag. As for getting diapers and wipes there, I just throw them in the stroller check bag I have and didn't have to worry about taking up suitcase space. Also the good things about clothes at that age is they are so small that they didn't take up much space at all so packing some extra's was no problem for me. However everyone is different and will certainly have different opinions. I'm pretty laid back and have done WDW many times so being their with little ones, while it was a different experience, was no problem for me and I have done it most trips by myself.