There appears to be some disagreement about "i" versus "p".

http://www.youtube.com/watch?v=Z-JXfyvlPh0

1080i vs 1080p

http://www.youtube.com/watch?v=DLeK8YAyDJU

My thoughts:

With a fast moving image, either the object moving or the camera moving, the 'combing' at the edges of objects with an interlaced picture can become very noticeable. Simply because each field will be of a different image, and when the image is moving in the 'frame', that difference will become significant.
So with fast moving images, a 'p' display of a lower resolution may well look better than an 'i' display of a higher resolution.

With slower moving images, the 'combing' effect will become insignificant. Effectively each field of an interlaced display will contain an image of the same subject. In this case the higher resolution display will look better, there will be more detail. So a 'i' display will have more detail than a 'p' display of a lower resolution.
Because the eye 'combines' the 2x fields of an interlaced display, they effectively become one image. I think a 1080i display of a slowly moving object will have more detail, and will look better, than a 780p display.

Having said that, it depends upon the scan rate. Some people are more sensitive to the 25Hz refresh than others, and I know some people find it annoying, whilst others can't really see it, maybe unless they use their peripheral vision.

Whether for general viewing most people would select 720p or 1080i I don't know.

If you are getting to that certain age, it happens to us all, you may need some of these to be able to see the picture properly, and be able to tell the difference anyway