In my opinion from prior experience having a 2008 48" John Deere Rider I would much rather have a zero turn for the improved maneuverability and ease of use especially for an older gentlemen like yourself. At Home Depot for around 2,800 you can get a Toro 42in with a Kawasaki engine which is very reliable and I have many friends that will stand by this product and if your looking for something a little bigger the have a 50in for 3,000. If these price are a little high trust me when it come to power equipment you really get what you pay for plus zero turns are a great investment and if taken car of have a good resale value. If you have your heart set on riders post back and I can give you some options.
Toro TimeCutter SS5000 50 in. 23 HP Kawasaki V-Twin Zero-Turn Riding Mower with Smart Speed-74631 at The Home Depot
Toro TimeCutter SS4260 42 in. 21.5 HP Kawasaki V-Twin Zero-Turn Riding Mower with Smart Speed-74626 at The Home Depot
Ryan, your comment about ease of use really held true with me. I mowed over 2 hours with my old rider and my arms would be worn out. A zero turn cut me down to a little less than 1.5 hours and don't feel tired when getting down. I have had some arm troubles and the zero turn has relived some strain on it.
Zero turns really were a great innovation they make it so much similar and easier. I will never buy a rider again the only down side to zero turns is the fact that rear tires can wear out very quickly if you make a lot of sharp turns on pavement or asphalt because only one tire is receiving power while the other is just being dragged or twisted around, its like when you turn a car tire at a stand still it will wear it out. Although they are totally worth it do to the increased productivity and high profits. It hard to believe that they have been around for over 50 years.
Ryan, if you turn like that you won't have much grass to cut after a week or so. Your going to find out that the z-turns don't have very many problems if used correctly. I'm 71 and I just switched to a z-turn and would never go back to a regular rider. It cut my mowing time in about a 1/3 or more and the yard has never looked better.