Why cant you stay at his villa???? does he live in shared accomodation or something??
Yes it is 'illegal' to share a hotel room if unmarried but everyone does it and unless you do something to cause attention to yourself (i am talking loud room parties, being drunk and disorderley etc) then nothing will be said to you and you wont be asked any questions.
You can book in advance and go up the burj khalifa which saves you about 300dhs, as on the dy just turning up is alot more than pre booked.
Go down to old dubai and go on abras over the creek, go to the souks and pick up some bargains.
Madinat is a great hotel to wonder round and have lunch, lots of little souk shops (do not buy from here though, buy from the actual souks not in a hotel as you will pay about triple for everything)
Go down to MOE (mall of the emirates) and do Ski Dubai (again this will be in entertainer) and then go to Dubai Mall to see the aquarium (again voucher in enetertainer that lets u see aquarium the underwater zoo upstairs and a boat ride over top of aquarium)
At dubai mall go and have a nice lunch and watch the fountain show, which i persoanlly think is better than the fountains at the bellagio in vegas.
Wild wadi or atlantis (wild wadi i think much better but most expats hate the atlantis hotel, very touristy and not that good!)
If you go down to Karama it is a town full of shops selling fake designer goods, some love it, some hate it.
Go for a massage or have nails done at one of the hotels or in the mall.
Down by the Marina there is a great little boat tour Captain jacks or something like that, you cant miss it.
The one and only royal mirage is a beutiful hotel and has a roof top bar for pre dinner drinks and then has a fantastic resturant on the beach called 'beach bar and grill' which is amazing.
'Frankies' is an amazing resturant (frankie detorris and marco pierre whites) down by JBR on the walk.
Friday brunch at the Al qusar is a dubai insitution! 4 hours of every food and drink imaginable!
Either of Gary Rhodes resturants are amazing.
The cheesecake factory at either Mall of the emirates or dubai mall is good for a lunch and cheesecake!
If i think of anything else i will add.