Heading to Vegas Monday through Wednesday and was thinking if staying at TI. I haven't been there for years but I used to enjoy it. Any thoughts on the hotel?  Any problems bringing friends up to the room?

Depending on the time of day there is no security at the elevators.
In the evening time there is usually security checking for keys.But sometimes even in the evening I have been able to come right up without being stopped.
Perhaps maybe it is a weekday versus weekend kind of thing.
Meet your provider at the bar or somewhere in the hotel and go up together.
The rooms are okay in my opinion some of the rooms need to be updated but it is clean.
Have fun!

The lovely Jaydalee is correct.  Stayed at TI a couple of times over the years and security has been consistent.  After 10pm you must show a key card to access the elevator banks.  Other times, no security on duty

I like the location, kind of in the middle of all the better casinos and resorts.  Easy walking distance to most places.  Security has never been an issue during the week, usually on the weekends the do key checks.  Price is reasonable for this time of year, however there are other places slightly off the strip that are just as nice and more reasonably priced.

But you can eiher meet at a bar and accompany your date or meet downstairs and hand off a key.
Either works
Im sure many ladies have keys.. I know I keep diverse collection.  
Never had trouble with Ti

They do have security at the elevators but it shouldn't be an issue going up for you two.  

Should be totally fine, haven't had any issues before.. Have a safe trip and fun one..    

best place is usually going to self parking. Mystere theatre area.