Every now and then, I fly into McCarran for Vegas when the fare is cheaper than the drive. The airport seems very fragmented with all the terminals scattered over. It may be rare, but I can see it being a real pain if you have to transfer here from domestic to international with short layover.
The rental is main rental area is off-site access via shuttle buses, so give yourself some times during the return. ... and even more if you are flying from Concourse D. They got the usually fast foods and few sit down restaurants, nothing to be amazed here. Over in Terminal 1, they have a museum to kill so times should you experience a long layover here.
For airport lounges, Delta is lacking presences here. Only United has one here, and there is a Centurion Club for the elite Amex members as well. I believe any Amex can purchase a day pass there. TSA Pre-check works here. If you dislike the Taxi, they now support Uber/Lyft here. Perhaps within my lifetime, I will see the Monorail extend to this airport.