I stayed at HP St.George, which I think is a great option. Only an hour or so drive to the visitor center. The visitor center parking lot had to be at least 75% empty when we got there at 7:45am on a Saturday in early summer last year. So you should be fine getting there ~8am or probably maybe even 8:30am.

We did the Angels Landing (permit required per lottery system), back down to the Grotto bus stop before noon. Even after spending an hour for lunch on the way out in Springdale, we were back at the HP in St George by 2:30pm with plenty of time to shower and pack before the 4pm Globalist checkout.

Without the Angels Landing reservation, you could hike to the Scout Lookout and back, add the popular Virgin Narrows River Walk, and have plenty of time to do all that leaving St George by 7am with plans to be back at the hotel ~3pm.