sedona, trust me, you don't need a taxi to see Nafplion itself. The streets are very narrow and the old town is build on the side of a hill, so there are many steps. If you want to get to one of the castles, then a taxi would be required, for sure.
On the other hand, if walking alot is a problem, then I'm not sure what to suggest, other than people watching in the main square, under the plane tree, which is what my friend Cliff did last month.
