Vendors address the flexibility issue by using side emitting LEDs. The flexible pcb also serves as a heat sink and tends to be wide. Flexing along the x-axis is hence difficult and could also cause a surface mount solder point to break.

There are tiles with embedded LEDs too. I would recommend thinking through the lighting effect you desire and going over the various possibilities in detail first. If necessary, talk to a local lighting consultant.

Here is a link that might be useful: Superbright led flexible and waterproof

Thank you - I have never heard of LED tiles. The site you gave me is useful. I spoke to an architect over the weekend who said that in ground lights would better illuminate the alcove than LED strips.

I've provided a led tile link.

Standard in ground lights may be impractical as the output could be too great. In addition, the required mounting structure could be substantive.

See if you can build arch structures that will hide lights from direct view and still use straight runs of led or high power flexible led which bends in the y axis. Some find tiny beads of lights distracting/ distasteful.

Here is a link that might be useful: Led in tile

I just noticed that Philips has a color kinetics product specifically for coves... I don't know anything about it and this used site is just the first I grabbed; they're available new as well.

The eW PowerCore LED light bars do output a significant amount of light. However, some creative craftsmanship in fashioning the cove to soften/ distract from the straight lines.

Thanks