there's always a card room running of course. if you're main strip you'll have a lot of options and wait lists are not a big issue except at bellagio IME. it depends on the game you want to play obviously but for smaller games unless it's weekend evenings you shouldn't have to wait long.
where you want to stay depends on your goals and how much you're comfortable spending on a room / how big your group is.
great thing about venetian is that the rooms are massive so you can easily have 4 people in there without feeling cramped so it ends up being pretty inexpensive for groups. and the poker room is pretty good. and the 24 hour restaurant, the grand lux, has a lot of great options that aren't a fortune. it's in a safe part of the strip where you won't have to worry about walking to others that're more central.
on a slightly tighter budget and going solo? want to still be in a safe spot? flamingo is a good choice. bonus: you can harvest flamingo 1s. it generally runs all night long. their tournaments aren't worth playing though.
on a tighter budget and don't feel sketched out by grimy rooms and sketchy people? circus circus is dirt cheap and has some of the most highly coveted 1s for harvesting. and the wynn is not that far away although i wouldn't recommend walking it with cash in hand. the wynn poker room itself is great for low stakes players - really nice room, they have uncapped games (not sure if it always is), they attract a lot of ballers because it's the wynn, and they serve complimentary frozen drinks (this may have changed). for low stakes grinding this is a top choice.
bellagio is overrated for small games because of the wait list. ceasars palace also not a great choice imo even though the card room itself is not bad. it's just really deep in the casino, restaurant options aren't great and all that's near you is the sports book. mirage is ok - the deli next to it is pretty good. any smaller than that isn't worth wasting your time unless you're already at the hotel for something and are looking to kill some time.