Hi
My hubby lives in UAE and we have visited him a few times. (In fact will hopefully be packing up next Spring to move out there full time to be with him)

There is a trip available from most hotels in Dubai, although we have our own jeep and have done it DIY, and that is for a day trip on a Dhow from Mussandam, which is an Oman enclave at the very north of the Arabian peninsula. You can get a half day or a whole day on the dhow, which includes food and copious amounts of cola/fanta/water etc etc, and you get to do some snorkelling. We have done the trip 3 times, including once when the sea was quite rough, and seen dolphins each time. They are just amazing, they ride the bow waves for a good few minutes each trip.

I can't help you with the canvas in the desert, as we do this DIY ourselves, but I would expect it to be cool in the desert overnight at that time of year. We camped in Mussandam at the Acacia Forest (worth a google), and needed 2 blankets in December.

I have seen a few adverts around for desert safaris, again we do this DIY with the Abu Dhabi 4X4 club, but however you get there, sand-duning in the desert is m*a*g*i*c!

In my opinion, although Dubai is generally cheaper than the UK, it is about the most expensive place in the UAE, as they cater heavily for the tourists. Abu Dhabi would be my choice, it is a cosmopolitan city but still has an Arab feel, whereas Dubai is more of a "global" city. Having said that, the Dubai Creek is well worth a look, and if you want to see ordinary non-rich people go about their daily business, then a visit to the "Neif" area beside the gold souk is a real eye opener.

Hope you have a lovely time
mgb

Jumeirah beach hotel is a perfect choice for you as it is one of the best family orientated hotels in Dubai. And with the free entance to Wild Wadi you cannot go wrong.
There are a few tour operators in Dubai who you can book the desert safari tours with, one of them being Arabian Advantures. You can book excursions with them at the Jumeirah Beach Hotel as they have an excursions desk at the hotel or you can book before you go. Although not sure if i would recommend doing an overnight stay in the desert with children. There are day tours which may be more suitable for children.