We stayed at IP several years ago and vowed we would never stay there again. It was very dirty and rundown, and even the non-smoking rooms smelled of smoke.
We're going to LV in a couple of days to celebrate our 7th Wedding Anniversary and we're staying at the Monte Carlo for only $69 per night. You can't beat that! I can't imagine that IP would be much cheaper. Plus the Monte Carlo is much newer, very clean, nice rooms & near other nice casinos.
Hope you enjoy your trip no matter where you stay!