What kind of oil is everyone planning to use?

[f5fstop]

You can switch between the two types of oil and not cause any problems with the engine. Synthetic is great for extreme conditions (desert, extreme cold), but in this day-and-age with the vast improvements made in standard oil I don't believe it is necessary (unless specified by the manufacturer).
GM spends millions of dollars testing these engines with different oils and as long as you meet the GM spec on the oil used, the oil should be fine.
They have also spend millions on testing the oil change indicator system, and it works great.
If you want to see if the standard oil is ok, have an oil analysis performed on the used oil to verify what the TBN of the oil is at the change. This will let you know if the oil used is holding up as it is supposed to in the engine.
An oil analysis also gives you details on the metals and other components in the oil and can help determine if the engine is in good internal condition.
After saying that, I use only Mobil 1 in my Vette, but that is what is required. In my Jeep, I used a good grade of standard oil; except in the time I spend each year in the desert of southern Utah, where the engine is put under a lot of stress and the temps range in the low hundreds.