I stay almost exclusively at TI.
As soon as you get checked in, before you buy one drink, sit down at a table, whatever, go to the Casino Host and get a player's card. Use it. Unfortunately, since TI went independent it's only good there (as opposed to MGM/Mirage which is good at a whole bunch of places) but you can still get comped stuff based on your play. Sign stuff to the room when you can. You'll be surprised how much they'll be willing to comp.
You are aware of the fact that they're charging you a "resort fee", as do most places. If you can't get that taken off, use it as much as you can. I'm not sure what all that gets you, but IIRC it includes the WiFi and the gym.
Isla is a decent place for Mexican food on the days they have the full menu, but the best Mexican food I've had in a resort type place is at Garduno's over at the Palms. Augie (Isla) is the world's greatest bartender and a hell of a nice person to boot. Avoid Kahunaville.
Steak--if money is no object, go over to Delmonico's at the Venetian or Prime at Bellagio. Most of the other places at Mirage and TI are so-so, although Canter's Deli at TI has some pretty darned good sandwiches if you're looking for something later in the evening. There's a California Pizza Kitchen at Mirage. Great lunch or dinner. Go for the gorgonzola salad. Buffets aren't the deals they used to be, but are pretty good for breakfast--TI breakfast buffet runs $14, IIRC.
Shows--MUST, MUST, MUST see either Mystere or Love. Both are shows by Circ du Soleil, both are great. Blue Man Group is over at the Venetian, as is Wayne Brady.
Gambling--pretty much the same wherever you go. TI's poker room is a cubby hole, more of an afterthought, very small. Mirage has a good one, as does Venetian and Bellagio.
And oh yeah--the "Sirens of TI." Free, but get there early. Might not be for very small kids as there's a lot of loud noises, etc.