Mmm... well, I can see your point there. However, as you're just arriving in the country, no one is expecting you to have riyals ready to distribute. Or I'd hope not.

Besides, the ATM spits out bigger bills than you'd tip to a driver (as in every country, UK included). So then you'd have the trouble of having to get one broken down.

If you're going to the hotel, and you really want to tip the driver, just ask him to wait for a second. Run in, tell them what you want to do, and change a bill. Or borrow 10 riyals from the bellhop, tell them you're changing money in just a second, and then give it back after you've changed money.

Truthfully, though, I wouldn't sweat it too much. You'll have other things to occupy yourself with.

Which hotel? The Intercon is quite nice. The breakfast buffet is gigantic. Literally 15 kinds of bread (at least). Fresh fruit juices. A whole long table filled with fruit and cheeses.