I went in 2010 and the tram on the Monte Carlo, Treasure Island, Excalibur side of the strip the tram is free.....

we rode it all the time between hotels

I have stayed at Treasure Island (had a very upgraded room and LOVED it) and NYNY, loved it as well.....I haven't stayed at some of the older hotels, but I think that end of town is very shady where The Stratosphere, Circus Circus and Riveraria are.....
walking through all of the hotel casinos is a must and they are all amazing! go check out
1.the White Tigers at the Mirage (not free but not very expensive)
2.Freemont Street (you have to catch a bus but it was only like $14 a person for an all day bus pass)
3.check out the M&M store (it is 5 stories on the strip)
the chocolate fountain at the Bellagio (have a chocolate covered strawberry from there...YUM YUM YUM)
4.If you have the funds, go see one of the Cirque shows...they are AMAZING!!!!!!(not Zummanity, it ias adult content

)
5.they feed the lions at MGM certain times of the day and it is free to see
6.go see the Bodys exhibit at The Luxor (amazing experience)...you can also see the Titanic exhibit (they are both paid things)
7.my sister went to the shark exhibit and said it was amazing!!!
8. ride the roller coaster at NYNY(pay as well)
9. walk through all the shoppes at the Forum at Ceasar's
10. Madame Toussad's wax museum is there as well (I have only been to the one in London)
11. you can see the Siren show at Treasure Island for free (starts at dark)