Firstly, what is your DSLR and what lenses do you use on it? The lenses are actually the really important part.
OK so this is something I've researched and considered for the past year. For
Disneyland Paris I took my S95. I shot everything in RAW and could then play with my pictures in Lightroom when I got home. I was happy with the results for such a small P&S and ended up with some 'perfect' shots. However, we have each bought a Canon 650D DSLR for our upcoming trip. Because I spent so much time in manual control on the S95, I want to use this for a DSLR and be able to get everything exposed correctly (i.e. clouds). I also wanted something that can handle higher ISO better (sensor's sensitivity to light)
I was of the opinion that I didn't want to take a DSLR to a Disney park because I didn't want to experience the holiday through a viewfinder and lug it round. My last trip proved me wrong. I missed not having the shutter speed to take 'frozen' shots in parades and needed it for low light performance in the evening. I felt I missed so many amazing opportunities because my P&S just couldn't do what I wanted it to. So this time I'm going equipped. I won't be caught out again.
My advice would be: if your pictures are something you really value and you really want to capture the magic of your experience, you may benefit from taking your DSLR. It can handle things a P&S just can't. At the same time, a beautiful shot is based on composition and the photographer's eye. You can take a great composition with a P&S.
But if you don't want to continually take photos and have the weight all day, don't bother with the DSLR.
You said you didn't want to take your DSLR because you don't know how to use it - but you can learn!!!! I think not taking it because you don't feel proficient is the worst reason not to take it. It depends on prorities and yes, there'll be times when you will use it on auto because you just won't have the time to set up a shot. But for those moments when you do have the time to set it up properly, or during periods of low light... why wouldn't you take it?!
If you're after a P&S, pick up a Canon S100. It's not cheap in stores, $500ish - but you can find it cheaper online.
I'm taking both DSLR and S95 on my trip because I can't be bothered storing the DSLR at Universal.