I live in Dubai Marina. I'd echo a lot of what Malced said.
The card you get for the monorail also applies to the tram and bus network, and they have packages at the airport where for around £30 you can get a local SIM plus 20+ journeys on public transport.
Download Careem app...which is a version of Uber, UberEats, Amazon and a car/bike/scooter rental. They have e-bikes and e-scooters to get around if you fancy a bit of exercise.
Don't come between May and September unless you like 40 degree heat. A lot of the activities depend on budget, but inexpensive things to do would be:
- Get a barge/souk from Marina up to the Gold Souk or Deira...or if you prefer something with AC, the ferry between Marina and Sharjah. It costs less than £5 for a return. For around £20-30 per person you can do the same journey at speed on a rib/speedboat.
- Hatta Heritage centre shows what Dubai was like before the money. Free museum with lots of interactive elements.
- AlSerkal is an art district in Al Quoz with lots of galleries and modern art installations. Not far from the subway so an easy place to kill a few hours and have a coffee.
- Deira is where a lot of the Indian/Pakistani/Bangladeshi workers live, and feels a world away from downtown/Marina. Some people hate it, but you can get a haircut/massage/tailored suit for about 10% of what you'd pay in the touristy parts. As a rule Dubai has almost zero street crime, but the few scams/pickpockets that get reported tend to be here in Deira.
- GroupOn and VisitDubai have loads of offers and last minute deals. It's constantly changing, so worth a look just before you fly.
Bars/Resto's:
*If you want to drink on a budget/in your room then you can buy booze from a chain called African and Eastern. You just need to show your passport (to prove you're on a tourist visa) and keep the drinks covered until you get to your room. Prices will be the same as in the UK.
*You'll see as much drunken behaviour in and around the bars at night as you would in England, but technically it's illegal, so I wouldn't go mad. You won't be locked up for staggering into your hotel or eating McDonalds on a bench...it's more that if you get in any sort of aggro or dispute with say a taxi driver or security guard...and police get called, you'll be de facto seen as the guilty party.
Good restaurants all along Marina Walk, by the waterfront. JVC or the Palm.
All the malls are worth an afternoon, probably Dubai Mall or Mall of the Emirates are best, but avoid them on weekends because they can get busy.
If you want to propose or something romantic, Pierchic is a stunning location.
Zheng He's does amazing Chinese food, again in a nice location.
There's also a restaurant/bar/club called At.Mosphere which is a hundred or so floors up the Burj Khalifa which is meant to have amazing views, but will be very pricey.
Lock, Stock and Barrel is a good bar with some great tribute bands...(Faux-asis
)
Barasti Beach Club is a nice outdoor venue with some decent drinks offers and a non-wankery clientele. Cana is a more upscale version but quieter and a nicer beach.
If you want a British pub then the Red Lion has a huge screen for football, and Biggles is a themed WW2 pub with a good selection of ales.
Let me know if I can be of any help.