Staying at one of the hike-in sites and hiking the Rim Trail (3 miles) + Bench Trail (4 miles) is great practice for backpacking if you are by yourself. You have a cell signal the whole time in case of emergency (good when you are backpacking alone).
I did two loop trails (Rim Trail and Bench Trail). Mileage reflects combination of both trails plus the distance hiking between the two near sunset point. Cost to camp in a hike-in site is ~$13/night. You can't reserve a hike-in spot in advance, but they are very under utilized. I'm pretty sure I was the only person in one of the 10 hike-in spots on a Friday night in September.
Hike in spots have a fire pit. There was plenty of wood just around the campsite, so no need to buy firewood. The only downside is that the flow of the springs (at least when I went) is not enough to practice water purification. You can go get your water refilled at the bathhouse near the drive-in campground.
The Rim Trail has some strenuous areas where you will need to scramble over rocks and/or hike pretty close to the edge of a large drop off.