We were just at the TI this past weekend. We go every year for our anniversary (we were married there in 96). We like this hotel because its simple to navigate, not too big, not too extravagant, but very nice. Stay away from the TI buffet. Even when its free, its generally not worth it. The cafe is very decent. Great breakfast food and fast service. If you like Krispy Kremes, you'll find a stand at the top of the escalator. TI hosts the Mystere show (Cirque du Soleil) which is very good. O is even better, which is hosted at the Bellagio. There's also a new Cirque show called Zumanity which has a more adult oriented theme. You'll find that one at NYNY.
Be sure to check the promotions page on the TI website (if you haven't already) and sign up for their mailing list as well. They offer many great mid-week deals. We recently stayed in a Tower room for $55 per night (+ 2 for 1 drinks at Mist and 2 free buffets coupons (yuck!!)). We asked for a view of the Venetian and we got a FANTASTIC view up the strip. We could even see the Bellagio fountains. If you don't request a view, you'll often get stuck with a view of the mall rooftop next door. You can also find some great suite deals on the web. Our last 3 prior stays at TI were either Suites or Petite Suites - both are great.
The standard rooms are very nice as well. You'll find lots of nice luxury soaps, shampoos, conditioner, etc. The room will have a blow dryer (if you need one) and a small safe in the closet.
As for valet, as someone else noted, its free - as it is at all Vegas casinos. One small correction though, you only need to tip ($1 to $2 is the going rate) when you collect your car, not when you drop off.
If you have any further questions, fire away!