Thanks for the suggestion. I wanted to avoid 3D initially, because I was planning to do my own artwork. I am pretty comfortable with vector/raster graphics but am not familiar with any of the 3D rendering programs. Plus, I like the style of the isometric games.
Dispite my ambitions, I will heed your advice and give Unity a try. There should be a good collection of pregenerated 3D models, especially in the Unity community.