Instead of having isometric graphics like IE games (BG, IWD, PT etc.) make it fixed perspective from above such as most RTS games nowdays like Warcraft 3 and Starcraft 2. This is almost the same thing gameplay wise, but will add more feel of depth to the graphics.
Making the background 3D on the other hand instead of flat 2D texture allows you dynamic resolution, dynamic lighting, more dynamic world, realistic physics and the list goes on and on.