If it's in your budget, LEDs are a good option and the range of available product is wide. Your electrician should be able to help you configure the lengths you want. The good thing about LEDs is no or low heat. They have very long life. You might even be able to use rope type lights and the length won't be an issue. Shop around. You will find amazing varieties. Be careful about polka dotting. If the lamps aren't close enough together, they could throw a pattern you might not find pleasing.

I have UC incandescent strips and it keeps my butter soft and spices warm in the cabinet above. The bad thing about LEDs is the potential to get unpleasant color if you don't select the right ones. Make sure you use a warm color temperature, 2700K or above so your kitchen light doesn't look blueish. A friend of mine put the wrong ones in and ended up yanking them out because they looked so bad. Go to a kitchen design store or lighting showroom so you can see different types of light installed. It wouldn't be a bad idea to dim them so you can just have a soft under cabinet glow when you're not working in the kitchen.

Good thing you have the rail. Mount the light as close to the rail as you can. Most people don't consider the fact that when you sit at the kitchen table, a light not mounted properly will likely hit you in the eye.

In our kitchen we have American Lighting T-2 bars. The color and fixture appearance are great but the life is short and they are a pain to change (easily broken and hard to find). We are building a new kitchen and have specified WAC Light Bars...LED without the dots...1" profile...90,000 hour life...available in 2700K and 3000K so the color is terrific. They are not installed yet but I purchased 2 bars in each kelvin for testing and they seem to be the way to go. Not sure but I think the sizes range from 8" to 24"...you can check out the WAC website.