So Marvel, what do you need so many "singles" for? Are singles $1?
Singles are $1 - need them for tipping everyone, or so it seems. I found it easier to purchase things like drinks, and smaller items using cash rather than CC for such a small amount.
We took around $500 cash with us. I lasted through Las Vegas only! Drinks, tips for the baggage people, house keepers, drivers, cabs, so many cab drivers don't take credit cards, or at least we found, paying for ART, and the list goes on. Only get $1/5/10/20 demoninations, $50 maybe, and $100s are a pain as they need to check for fakes and a lot of places won't take them.
An idea if you're going to Las Vegas is to get some Traveller's Cheques - American Express with post office pick up was really good. With enough notice we were able to get them commission free and on a really good exchange rate before we left Australia, purchased in USD, then cashed then in Las Vegas in a Casino Cage commission free

as well. Easier to carry than cash as it didn't take up as much room in our purse/wallet, safe, and we could then get a bit more cash into the holiday without using an ATM and paying more fees for that.
We also used them like cash in DL and they gave us change as cash, commission free.
Mickey's Halloween party at California Adventure. We have decided that it is a must do - the kids will probably never see Halloween 'American style' again. The candy looks pretty good too
We didn't do it last year - we were there around Halloween, and I wish we did. We're planning for the same time next year so we will do it then. Miss 6 has decided to "go to America so she can have Halloween as a ghost" so I think we shall do it next year.