I haven't driven in either place, but I've been to plenty of places with worse traffic than Dubai. Though if you hired a car, you'd want to have a good GPS navigator of the type that tells you which side of the road you should be moving to with plenty of warning - as there are lots of multilane roads. Traffic in Abu Dhabi didn't seem as dense as in Dubai the day we visited.
I'm a bit puzzled by the "wonders" in Abu Dhabi. I assume this means the sites are outside Abu Dhabi, because in my DK "Top 10 Dubai" book, Abu Dhabi occupied only a few pages down the back of the book - and there wasn't much listed. On our day trip to Abu Dhabi, the bus stopped outside of the main city at the Formula 1 race track hotel complex and at the Ferrari World amusement complex, which wasn't of great interest to me.
Certainly the Grand Mosque in Abu Dhabi is worth a visit, though your wife will probably melt with all the gear she has to wear to be allowed in (after spending $50 on a head scarf for her, I had to spend another $100 on a jumper because what she was wearing was deemed "see-through" even though one couldn't possibly see through it).
And there is a hugely long promenade area adjacent the sea that may be worth a very long wander, if you can handle the heat. The other big landmark is a huge luxurious hotel - but at the end of the day, it's a hotel. I really enjoyed the shopping centre we visited there - mainly because it was cool.
Please let me know what else is there after your visit, as I'm thinking of flying Etihad and stopping there next year.
Regards,
Renato