Hi,
We drove to Abu Dhabi about 6 months ago. It's not all that bad, just know everything will take longer than you would expect and you'll be ok. There is a place down in the souqs to get the transit visa for KSA, it was pretty easy once we figured out where to go. You know that white mosque with all the pigeons around it? Near the McDonalds? If you stand with your back to the white mosque, look across the main street and slightly to your left. On the top floor of the souq building there you will see a sign for Al Hissan Services (or something like that, I can't remember the spelling). Go there. The office is barely more than a desk and a guy at it. Go there and ask what you need (stuff changes all the time!). But, be aware you most likely need a letter of no objection from your sponsor.
Also, be aware that a woman cannot travel through KSA without her husband, brother or father...

OH, and very important!! When you LEAVE the UAE, you will have to PAY! We stopped at the last restaurant when leaving the UAE, spent our last dirhams on lunch then crossed the border. At the last checkpoint (there are several) they wanted UAE dirhams from us (can't remember how much). We said we didn't have any so could we pay by credit card. No, cash only. Ok, where was the ATM? No ATM... Hmm, we can't go back into UAE but there's no ATM and they don't take credit cards. We all just started at each other for a while, until someone "took care of it"... Ah, gotta love life in this part of the world.