While remodeling our bedroom we are considering recessed lighting. The bedroom has a seating area also - the bed area is 14' x 15' and the seating area is 10' x 9' (overall length is 24 ') and the ceiling is a step ceiling (30" from wall and 8" high). Each area has a light switch which controls overhead lighting. Would the recessed lights (assuming 4" lights) spaced every 4 ft and 15" from the wall (1/2 the distance of the step ceiling) be adequate (assuming a 40-50 w bulb?). We also have 3-4 lamps in the room also.
In general I think you are better off having too much light versus too little. If you plan using 50w bulbs, and it turns out to be too much, you can always use lower wattage bulbs or a dimmer.
Be sure to take into account the reflector type of the bulb as this will dictate how much the light spreads.
I disagree with Justin K because if you have too few lights, you start to get shadows and dark spots and assuming you're already at the max wattage, there is nothing you can do to improve the situation other than install more cans.
I would go to more like 6' spacing. One in the corners and one in the middle. I think a lot of people are overdoing it with recessed lights. The ceiling starts to look busy and the more lights the more electricity you will use/waste. How much light do you need in a bedroom? In my 14'x14' bedroom I have one 6" in each corner and its more than enough. I installed a dimmer to cut it back. The higher the ceiling the more the light spreads out so the less you will need.
i find in general that you need a minimum of 100 watts (apparent lighting watts, not power consumption) of light for every 100 sq ft, with the ideal being about 100 watts for every 50 sq ft however, it depends a lot on the bulb itself. falloff factor, angle of intensity, height of ceiling, etc all directly affect the overall appearance of the rooms lighting and appeal. you also need more light in a kitchen, less in a bedroom. its entirely subjective. however, speaking from many exit interviews with clients, most people always find they didn't put enough lighting in. so - i would go 36"-48" between cans (no more). put in extra switches so lamps, pots, areas, etc are all controlled from the switches. that way you can turn on and regulate whatever area strikes your need or fancy by using dimmers.