What do you recommend for prostate cancer in a person over age 75?

It depends. Treatment for prostate cancer depends on many factors. If the disease is localized to the prostate, radioactive seed implants, prostate radiaion, or prostatectomy is recommended. Observation without specific treatment also may be appropriate. If the disease has spread, observation, drugs to suppress testosterone, or removal of the testicles might be recommended.
My first answer is. "watchful waiting." exceptions are: gleason score >/= 7, psa rapidly rising after 3 tests a month apart, perineural invasion. Seeds are great for low volume low gleason. Higher volume and glands greater than 50 grams require anti-hormones: unpleasant effects, decreased quality of life. External beam done expertly has few advere effects and great control.
Risk stratification. Go to nccn.Org this site will tell you if you are low, medium, or high risk prostate cancer...Based on that info using gleason score, psa, bx details ...You can be risk stratified...While surgery is rare for someone over 75 it really depends on your health status and how many years you have left to live....I have treated men in there 80's with gleason 9 cancer...But not with surgery....