Turning 75 in a few weeks. My wife says "Get something real nice." Not necessarily a bike. So, I have been contemplating my riding goals (continue with 20-40 mile relaxed and, enjoyable to me, rides; some mtn biking; and riding with the wife), style (I don't give a hoot about speed, competition, racing, pacelines and the like), fitness goals (swimming, resistance training, walking, bicycling, targeted stretching - all to maintain muscle structure and aerobic capacity - which seems to me to rapidly deplete about this time in life, AND, I greatly enjoy these activities). So, I have decided that my current stable of 1999 Lemond Buenos Aires 105 steel bike with carbon fiber fork, 2006 Specialized Rock Hopper mtn bike, My Windsor Leeds 2002 "utility" road bike - heavy with panniers, etc. but GREAT for riding with my wife as it keep up nicely with her hybrid - she is 76 and will be 77 shortly after I turn 75, and my Specialized Hard Rock as a trainer in the basement are the perfect match for this guy.
What I will do is get some work done on the Lemond - it needs new cableing, a good cleaning, new chain and possibly some drive train parts and I might go for a better set of wheels, although nothing wrong with the current set. The bike shop up the street has a deal for $150 with includes most of the above and more (except the wheels and parts).
There! I think I have sorted out my 75th birthdy present!! Get the Lemond in perfect order. I don't work on (nor enjoy working on) bikes except to pump and change tubes and tires and lubricate as needed.
Incidentally, I get a lot of positive remarks about the Lemond - especially from folks in bike shops.
For me, enjoyment of whatever one does (whatever that means to you) is the key to long-term physical activity.