Originally Posted by Lost

Check flights out of the regional Cedar City (CDC) and St George (SGU) airports first. If those are too expensive then Las Vegas would likely be better than Salt Lake (LAS is about 80 miles closer depending on exactly where you start from). The construction project on the Arizona part of I-15 was completed a few weeks ago so that's not an issue anymore.

Also estimate how many different parks you'll need to pay admission to and whether it'd be better to get an annual pass. An annual national parks pass is $80 for 12 months and is good at all national parks (so think about any other parks you might visit in the next year).

You can buy it ahead of time, but it'd probably be easier to get it at the first entrance gate you pass through. Mine has paid for itself several times over already.