As i said, not all the compounds in riyadh permit single men to live in them, there are strict rules on the leases. Seriously, if you can spend 4 days in Dubai, then max 3 in Riyadh.. then I´d live in Dubai, and get the company to pay for your accomodation.
Rent has increased a lot this year in Dubai, but is expected to stabilise in 2008, as more property is completed. You can search online, but it is vital to know where the offices are located in both cities... transport will be by car or taxi, the latter is not great in Riyadh. Our office there is right next door to a serviced apartment complex, which is very very handy, where as in Dubai, getting to work can take a very very long time, and they´ll be hardly any parking.