The 2600 has a large well organized color palette.

The colors are crystal clear on an emulator on my computer screen.

The problem is the colors may not look like you expect on a CRT TV.  Here's some bad examples:

The ghosting is so bad on some of these colors you can't even tell what you're looking at!  Here's some good color combos on my CRT (Sony Trinitron):

There's still ghosting, but you can tell what you're looking at, and from a distance it looks really good to me.

Just because the colors look good on one CRT doesn't mean it will look good on another CRT!  Two of my CRTs were kind of dark so I brightened my colors to look better on those TVs.  I was able to go into the TV settings and adjust the brightness, but not everyone can figure that out.  I had this cheapie red CRT that looked great with some colors but with the pink and purple combos I could see static on the screen and hear this annoying buzz... but only on that TV!  At one point I had large set of 32 different color palettes!  I kept adjusting some of the palettes to try to get them to look good on all my TVs but it just wasn't happening.  I went for quality over quantity and cut the palettes down to 16.  I also borrowed and sometimes modified palettes from other games - blue maze from Ms. Pacman, Chopper Command, Missile Command, Mr. Run and Jump, etc.  I figured if the colors looked good in those games those same colors would look good in my game too.   

I'm color blind by the way.  I don't think this is a very big handicap but I do perceive color a bit differently than others.  Maybe we all perceive color a tad differently?  Or even a lot differently?  Shrug?  Who knows.

Anyways here's my final palettes.  Maybe I should have included ships on this collage as well.

I tried to order the palette changes so they aren't too jarring to the eye... like going from black directly to a bright white screen.  I also tried to sort the colors as best I could.  I think it makes transitions from one palette to the next look nicer than just a completely random color change.

I implemented the black and white switch functionality early on.  I felt pressure to cut that feature many times for a few extra bytes and cycles, but somehow it survived to the end of the project.  The intention of the Color/BW switch is to make games look good on a black and white TV.  Adventure is a perfect example of doing that.  In my implementation I just mask out the color components of my ... colors.  My implementation isn't perfect.  I think a few palettes have ships that are the same shade of grey in black and white.