From your description, no, nothing obvious.
For the cards you use and their overseas charges, does it make sense for you to make smaller purchases by cash ?
Of course, it doesn't hurt to have a few Dhs in your pocket for emergencies, but there are ATMs everywhere and you can suck up the occasional withdrawal charge.
From memory, where you would need cash:
- most taxis
- shopping and cold drinks in the souks
- crossing the creek by abra (1Dh coin
)
- some street food, e.g. fresh coconuts on the creek side
But cards are accepted everywhere else - malls, stores, restaurants, coffee shops, etc.
Enjoy Dubai. I know it's not to everyone's taste, but I love it there.
hth