What Scott said, mesa arch is nice in the morning, but it is the morning and I have never been successful to get both me and the wife there at the same time. also, the approach to mesa arch is quite pleasant. the approach to delicate arch is a mile-ish and generally quite moderate. sunset is usually a good time, but you may want to check out google earth to see if delicate arch will be blocked prematurely. Generally, sunset is ideal for delicate arch, there will be photogs lined up and someone usually tells the kids to get out of the way once prime shooting time happens.
I also recommend the needles district of canyonlands (south of Moab, towards Monticello). it tends to have less people and there are some very cool formations. Depending on how serious you are, there is an excellent 10-11 mile loop around the needles that will take the better part of the day. But, it is fun, you see a lot and there are even some mini slot canyons you can play in. I can dig up info if you are truly serious about doing it
Also, I would suggest Goblin Valley State Park. There is a lot of cool stuff near Hanksville, including the famous spot where Aron Ralston had to cut off his arm in Bluejohn canyon. Depending on how much time you have, you may want to explore other parts of southern UT which require more driving.
The wave is always an option (pending permit), and the Paria canyon offers numerous unique features. Escalante is excellent as well. I can't vouch for the photo opportunities too much, as I mainly back pack through the area, but the drive through Escalante up to Capitol reef is nice, and there are many 1-4 mile hikes one can do (I can send some pages from my hiking books if you are serious).
I'd offer to go with you, but we have an impending bambino scheduled for tomorrow. I'm sure my wife would poo-poo the idea, although I generally don't have to twist her arm too much to go to Moab. It's a slight possibility.
i've done the drive in 3.5 hours, but I would plan for 4 if the roads are clear and there is no traffic. they have construction on I-15 around Provo/Orem just before you get off at Spanish Fork to head towards price. If leaving in the afternoon on a weekday, I would budget more time.
it should be pointed out, that a lot of these sedimentary formations are present in the desert b/c of wind. Cold is one thing, very windy conditions is another.
lots of options. one could spend their entire life there and not see it all.