score:3
Would that be enough time to get my luggage, clear customs and board the other plane?
I would give it an 90%+ chance of making it. I came into Houston from Peru about 2 weeks ago. International flights are still pretty empty (as compared to domestics ones, which are often stuffed to the last seat). Since I have Global Entry and no checked luggage it took me less than 5 minutes to clear immigration and customs.
Your timing is helpful, there seems to be a big spike in incoming passengers around 7am although sometimes it spikes earlier as well. A few preperations to make things go faster
If you miss it (by no fault of your own), United will still get you to Vegas and rebook you for free on a different flight. It's early in the day and there plenty of other options to get there.
Upvote:3
2 hours should be plenty of time to make this connection, presuming that your inbound flight isn't excessively late.
Although you will need to collect your bags at Houston and carry them through customs, they will have been tagged at check-in all the way through to your final destination which means that you will simply need to drop them at the bag drop after customs/immigration, which is fast. You'll also have received your boarding passes for both flights at check-in, so again no need to wait.
You will need to clear security again in Houston. The fact you're flying on the Sunday after Thanksgiving means that this could take longer than normal - although at ~6:30am in the morning it should be less of a problem than later in the day.
The good news is that if you don't make your connecting flight, United Airlines will simply put you on the next available flight to your destination. The bad news is that being the weekend after thanksgiving, the next flight with seats available may not be until much later in the day - although looking at the current flights IAH-LAS for that day it currently appears that they are not as busy this year as normal years (but obviously a lot could change in the next 7 weeks!).