Hi, Motelmat. Looks like you're in the same age/health category as my husband. We, too, debated all the options and did three months of research before making a decision. It is not an easy one and the doctors are not much help - each wants you to choose his/her specialty, or they simply expect you to make in informed decision based on what you can find on your own.
Regarding radiation, note all of the above. Plus, we discovered that while we stood the chance of temporary incontinence/impotence with surgery, that radiation can affect you the same way 6 months or 6 years down the road and it could be permanent. Plus the bowels can sometimes be involved and even destroyed, leading to colostomy. Those are extremes, of course, but we wanted to enjoy a full life as you do (well into the 80s and longer) with as many faculties intact as possible. If we need radiation at some future point, at least it's still an option following surgery. Plus, we also know what we're dealing with pathology-wise. If they had not inspected the gland post-surgery, we would not know of additional involvement until perhaps a year down the road. With radiation, it takes that long for everything to settle down inside before receiving an accurate PSA test.
To me, a healthy 66 year old (or even older in good health and based on clean scans, etc.) is an excellent candidate for surgery. Age has nothing to do with the type of decisions available; health, emotional outlook and expectations, and cancer staging do.
With surgery, you stand every chance of no repeat treatments. With radiation, if something is needed in 10 years, you're facing that at 76, instead.
Just wanted to add to the confusion. ;-)
Husband age 65
PSA on 5/1/06: 4.2 (had doubled in 13 mos. and rising monthly)
DaVinci Surgery 8/2/06
T2a (at biopsy)
T4c (at pathology) w/cancer cell leakage into fatty tissue
Post-Surgical PSA on 10/3/06 - undetectable!
Update: 11/1/06 - perhaps bladder neck involvement; 30%-50% chance of recurrence
Future: PSA tests twice-yearly for now