Wood would be a popular option.

For me to provide input, need to know more about your existing home and porch design. Can you upload a picture or two?

The house is under construction, so I don't have existing photos. We were going for a beaded board look using hardi board siding. The seams between the 4'X8' sheets are obnoxious, so we're looking for a solution to rectify the problem. I took a cell phone picture previously, but it truly does not show the problem.

This is the celling i have. It can be lighted in the night. I put lamps between the bamboo and the celing

on the ceiling goes a very nice a stencil in sgraffito

Just to echo what Kevin Patrick O'Brien said - the 1 x 6 plank (or "Car siding") can be beautiful stained or painted. You can also get it with one extra V grove in the middle if you want a smaller plank look. Since it is wood, it will move and require more maintenance than Hardi. We have also done some with 2 x 6, where the material actually became part of the structure of the roof above. Probably overkill for a porch though. (By the way - the term Car siding came about as they used to plank the inside of railroad cars with it).

Here's the 2x6 pine on a ceiling in a patio kitchen.

Here is a very simple way to create a great ceiling. 4 x 8 sheets of whatever, here we used cedar plywood, with batten strips to cover joints and create a pattern. this porch was left natural and rustic without breaking the bank!