Do not use the casino entrance, unless you like to walk a lot
. Vegas casinos are all bigger than they look, and that applies inside as well. The back entrance leaves you right where all of the rooms and registration area is.
Depending on which room you are in, it is best to walk back towards the casino for bathroom breaks; that goes against what I just said, but the lines are shorter, and after 2 hours sitting, not so bad to stretch your legs.
There are some good eating options across the street at the Gold Coast; eating at the Rio is expensive, and not as good.
Be prepared for hawkers in the hall to sell your phone chargers. There is usually a D&B stand that has their entire library, if you want to buy a book or 2.
There is a tax consultant, who is also a poker player for foreign withholding issues. Clayton financial is a local firm (that I use) that specializes in gambling as well.
There is at least one set with a 25K chip that looks like smaller denominations. Check your chips and denominations before you play.
If you cash in a very large event, that payout lines can be quite long; once you have your card with your finish, you can come back later (this was true in 2019, CHECK to make sure this is still correct).
Lines for registration are also quite long. Remember, you need your player card and ID to buy in. You can register for more than 1 event. I think you can register for any event up to the last, once the first opens.
You can put money in an account for buy-ins; not sure how this works, I don't do it.
In the past, all the other casinos ran series simultaneously; if you are here for longer than a few days, consider playing elsewhere, especially if the event doesn't suit you. If you want to just stay at the Rio, they always have cash games, and sat's running.
Wynn is the best for other series, Venetian is good, but higher rake, Orleans has a bunch of mixed games with 3 figure buy-ins and soft fields.