I think it would be great to paint it a lighter shade. I'd suggest going with a soft shade of blue like BM silver cloud.

Here are some images that might give you some ideas. You'll see that you can do any variation you want and it all works well.

Here they put the crown on the edge of the tray to make the tray seem even more recessed. This ceiling is also a bead board and done in a contrast color.

Kitchen · More Info

Here, they turned the whole bump from the lower ceiling up to the edge of the tray into a white ceiling color, giving the look of an extreme molding treatment. But they kept the tray color the same as the wall color.

Park Hill Renovation · More Info

In this room, they painted the lower flat white and kept the upper flat the same as the room color. It lends a cozier feel to the space. But with the upper crown white as well, it is more stripe-y.

Mary Trantow · More Info

This is a more modern look with no crown and the entire ceiling being done in a metallic, it makes the room far more horizontal vs. tall.

Contemporary Bedroom · More Info

Here's one without crown or color differentiation at all. Rather it's just the shape that defines the tray.

Lake Country Builders · More Info

Here's more like what you're talking about with the wall color blending up onto the lower flat to the upper crown, but with an accent color in the tray.

Naples Design Project · More Info

This one is more coffered than tray, but will give you an idea of what pale blue can do to a ceiling.

Sater Group's "Villoresi" Custom Home Design · More Info

Here's a room where the wall color goes all the way to a crown at the upper flat. Only difference is they painted the upper flat darker rather than lighter.

Lakeside Living · More Info

Here they painted the entire ceiling one color, molding and all.

Kewamee · More Info

Here's a room without crown, wall color up to upper flat and pale ceiling.

Bedroom · More Info

Yours could be more like this only you wouldn't have the lower crown.

Portfolio · More Info

Here they kept the same color throughout, but added the crown to the bottom of the tray to make it more outstanding.

Santa Barbara Hope · More Info

Here the lower flat is the same as the trim. The upper flat is a lighter shade of the wall color.

Fabulous City Living · More Info

I'm sure there are more combinations and permutations, but you get the idea...it's all about the look you are going for.