For visibility and nothing more, you can just use a moonlight blue bulb of low wattage above your enclosure at night and a simple day bulb for day. Normally no more than 25 watts for simple viewing.

If you're using them for supplemental heat, make sure the lamps are at least 8"-12" above the lid and use 50watt or lower bulbs. Anything closer or higher and your humidity goes POOF.

Red lights cannot be seen by the snake, but many people (myself included) have found that the intensity of those bulbs actually causes their snakes to hide more. So, between red and blue, the blue would be less intense and, IMHO, nicer to look at.

Just my