Some colors can be made brighter than others, but for the most part, yeah, EL Wire looks rather unimpressive in brightly lit environments.
Batteries are a low-voltage DC form of power. EL wire requires high voltage AC power. To use EL wire portably, you use a specialized device that oscillates the current at the appropriate frequency, and then ramps the voltage to the needed level. You can build them without too much difficulty, but most times, you're better off buying a premade one from a specialty supplier.
Regardless, it looks like you merely need relatively small panels to light up. You can do this perfectly fine using a combination of LEDs and optical diffusion film. Diffusion film blurrs light sources, and spreads the effect across a wide surface. One good example of this are the ForceFX lightsabers. If you take one apart, you find a boring old chain of LEDs; but thanks to the diffusion film, it looks like a solidly glowing rod. And so long as the LED is bright enough, it looks just as solid with a single LED at the base of the blade.
You can order specialty film online (in fact, there are some suppliers for the custom lightsaber community that are a good source for the stuff). In a pinch, you can just take a thin piece of clear plexiglass (scrounged, or purchased at the hardware store or hobby shop) and scuff it up thoroughly on the underside using around 400-grit sandpaper.
To get it to glow the right color, you can either find plastic film that has been tinted your desired color, paint the plexiglass surface with premade "stained glass" acrylic paint, or make your own acrylic paint by mixing a tiny bit of artist acrylic paint with artist acrylic medium. Acrylic medium is like paint without any pigment in it, so when mixed with colored paint, you get a pigment concentration that is low enough to make it translucent, but won't make the paint all thin and drippy the way it would if you just mixed in a bunch of water.
You'll want to build some sort of small frame in order to securely mount the LED a fixed distance away from the film. You can do this with wood, bits of sheet plastic, or if lazy, you can just encase the LED(s) in hot glue.
For maximum brightness, you can either glue in mirror-film or brush it with reflective/metallic paint.
When purchasing LEDs, make sure you get the stats for the LEDs and do the math to figure out how to appropriately wire it up with the proper voltage and resistor values. Leaving the resistors out wastes the battery and reduces the life of the LEDs.