I have 6" cans, which are fine, and shed very good light. But I actually prefer the 5" size, which, to me, just look more modern. I wouldn't go to 4" size though, because you'll need more of them and your ceiling will be like Swiss cheese.

We have a combination of 6" and 4". The larger ones are in the areas where we need light such as the kitchen & entryway... and the smaller ones are in accent areas by the fireplace, in a small hallway in the master suite and in a small cutout we have between the foyer and dining room.
I think the smaller ones look nicer, but the larger ones give better light.
L

I like the 5" cans as a good compromise between aesthetics of small size holes and getting good light out of bigger size holes. The 4" ones just don't put out much light and agree with the "swiss cheese" description above.

I like the 5" ones. The electrician first put in 6" ones (by mistake) and they felt too big for my space. The 5" seem just right size wise and light-wise.

IMHO 5" is a good compromise. The 4" seem more appropriate for specialized situations rather than affording good task lighting. I would also recommend that you choose the trims that best blend in with your ceiling. We used the Juno 5" cans with the Wheat Haze Alzak trim. The outer ring is white, and the inner cone is the almost invisible. This keeps a white ceiling from looking like it has a bunch of black holes in it when the lights are off, and the Alzak finish greatly reduces the glare when they are on.

Here is a link that might be useful: Juno

I chose 6" Juno cans for my renovation b/c that is what is in the rest of the house. My lighting consultant uses 5" cans as her standard.

Ceiling height is a factor. I have almost 10' ceilings and a combination of 5" and 4" cans. The 4" ones are in pairs over the sinks, where their twin beams just covers the areas (they have a smaller beam spread even though they're nearly 7' above the counter) and the 5" cans are everywhere else. . If you have lower ceilings you have to take that into consideration to get the same coverage. Means you need more cans, or bulbs that put out a larger cone of light. But the intensity also diminishes with distance. So, the extreme case would be that if you had an infinitely high ceiling, you could light it with one can, but the wattage would have to be like the sun's.
I chose to distribute my 5" cans toward the "bare minimum" side of things. I did one grid of four centered on the range/main sink triangle, and then added other cans to highlight certain things, like the wall oven /china cabinet, the fridge, and one separate can on its own dimmer at each entrance.
It's a lot of light, not perfectly even, but it doesn't overwhelm, and everything is dimmable. I also have undercabinet xenons, which are indispensable, 4 @ 22 watt halogens in the vent hood (indispensable) and two sconces that wash a wall area. IOW, don't put all your eggs in one basket. Light coming from a lot of different sources, and a lot of it on dimmers, gives the most flexibility to a lighting plan.
Casey

This is a great topic for me. I have the final meeting with my electircian tonight before he starts work next week. He has 4 6" white cans specified for our 7'8" ceiling plus a 6" can over our sink. I am now wondering if I should ask for 5" instead, or if with the lower ceiling if 6" still makes sense.

We have 8' 4" ceilings and the 5" cans have worked really well for us.

zelmar, how many do you have and how widely spaced apart are they? We have 8 foot ceilings and we're thinking of putting in a row of 4 6" ones 40 inches apart. After reading this, it sounds like it may be a good idea to get the smaller ones.

dcwesley, let me know what you decide on. What's the spacing on yours?

Another question, how far should they be from the wall to make sure the counter is well lighted?

6" units isn't so bad in 8 foot ceiling. I freaked about this issue too worried they might look huge. But when installed they look fine, good flood of light too so you don't need less.
4" would be for accent or supplemental lighting.

I would do about something like 16-20" from the wall if your wall cabinet is 12". Basically you want lights above the counter top. Some will be washed over the cabinet doors but not so bad.

The layout is difficult to choose and you may want to ask your electrician or KD. Or try to distribute evening given a number of lights.

Wow, thanks for all the great feedback. Before today I was going with 4", I think now I am going to use the 5" and maybe add some 4" for some tasks like over the sink.

I have 8 ft ceilings and room is 13.5' x 23' for those that asked.

So now onto my next few decisions. I see that I should put the cans over the edge of the counters, seems pretty simple.

1. I will have lights above the stove (integrated into my range hood), is the light I have planned near the stove overkill and will it cause shadow issues?

2. Regarding the walkway between my island and pantry-fridge. This is the walkway when entering the room on the right side of the pics. Should I center the lights above the walkway or is it best to locate the lights closer to the pantry cabinets?

3. Does anyone have any suggestions on my lighing plan in general. I will have lights in 3 glass cabinets, lights above all the cabinets, lights below cabinets.

That looks ok to me.. I would try to move the light bulbs a little closer to the counter top or your head will be
casting a shadow over the usable light. This may not be an issue if you use your undercabinet lights all the time but I setup mine so that the undercab lights enhance the overall light but not absolutely required to be on.

I might also choose to keep the sink one in line with the others and add another little 4" units (or pendant/cool fixtures) or two above the sink.

One near the fridge is good when you open the door it actually helps to see what is inside the fridge.

Ok, so the general oppinion is to go with 5" cans vs 4". Is there anyone that would choose the 4" over the 5" and if so why. I like the look of 4" lights, but it may take way too many.

So I adjusted my plan as seen below. I now have all 5" cans in the design and they are space 48" apart. The light over the sink will more then likely be a 4" task light.

Is my 4ft spacing ok, or overkill with 5" cans for this size kitchen? This spacing works the best with my rafter locations. If I used 5ft spacing I think it would look odd having a light not centered near the sink down the main run.

joep 2009---our five 5" recessed lights along the perimeter counters are about 50" apart on center. They give off a lot of light, I feel as though I'm turning on the landing strip lights when I flip the switch. It turns out I really didn't need them since I have task fixtures over our most used areas---the prep peninsula, 2 sinks and range (in the hood).

We do have three additional 5" recessed lights that are used as the main overall light of the kitchen (2 along the walkway and one in the middle of the work "u".) The 5 perimeter recessed lights get used very rarely. I guess the point is that they work really well, almost too well. My kitchen is 13.5' x 16'.