Almost forgot to give feedback.
We stayed in Doha between X-Mas and New Year 2011. Had a great time. We had our own transportation, a regular sedan car, 2 wheel drive. During winter season apparently suitable enough for desert drives (not too far mind you: take care, take plenty of water, food etc.), provided it has not rained for a couple of days. Managed to find 15 caches in a few days, mostly in Doha, some in the north and some to the west. All fairly easy to reach, not too difficult.
We pretty much checked the list we received from cincol. Did not encounter any problems. Beware in the vicinity of mosques: although the religious police allegedly ceased to exist, some 'regular' law enforcement officers frowned and approached us when we were parking too close to places of worship.
Thanks all for the help, especially cincol, who we unfortunately did not meet, since he was not in the country during our visit.
Qatar: you must have seen it!!
doofie