Hi, Todd, and welcome to the club!
I have owned and flown 150s and 152s in the Boulder/Denver area for quite a few years. The 150 will do just fine but you have to accept its limitations. At our elevations, climb rate is reduced and take off roll is longer. Airspeed management becomes more critical.
It will make you a better pilot.

I've not flown mine off of grass at our elevations. A lot would depend upon the condition of the strip.
Something to consider is your size and the instructor's size. The 150/152 has a small cabin and a limited useful load. Two big guys in one at 5000 MSL is probably not a good idea.