I have had a host at several different casinos, including Venetian and Cosmo.
Now, I have a host at a "locals" casino

I have never tipped my host and don't know why you would. In addition to their salary, hosts earn bonuses based on the amount of money you lose. YUP, a percentage of your losses. Whether you choose to believe it or not, hosts are rooting for you to lose, and so why oh why do you think they expect tips?

I am treated very well by my current host, who goes out of his way to make sure we have the same suite each stay, RFB.

We have winning trips and losing trips, as that is gambling, and it doesn't affect our host's friendly demeanor, as he knows the law of averages . . .