I have a 58cm bikesdirect fantom cx.

Great bike, but it's a bit of a reach. I end up using the cross brakes too much, not enough the hood brakes, b/c I think the stem is too long.

The stem is 110 mm.

I am 6 foot.

I am thinking of picking up either a 60 mm or a 70mm stem.

I looked it up, and it appears that the 56cm version of the fantom is about 10mm shorter in the frame.

When I ride the bike, it is a reach to reach the hoods. The most natural place to put my arms seems to be around the place between the straight and forward section of the handlebars.

thoughts?

I would use a 70 MM or a 80MM stem.

Yeah, I'm starting to think a 90mm stem should do the trick. a 70mm stem would effectively make this a 54cm bike.

Unfortunately, this is a question similar to the spoke length question posed earier: There's just not enough information to go on.

You're 6' tall; OK, that doesn't tell anyone how long your torso or arms are.
Stem length is going to vary based on how you have your bike configured. If you have the seat way back or way forward it changes the reach. Realize that a drastic change in stem length might necessitate a change in stem angle or number of spacers to keep a consistent bar height and not throw your positioning off even further.

Talk to your LBS and see if they'll let you try a few different lengths out before purchasing the one that feels right. Otherwise, you have to deal with the hassle of returning stuff from an online purchase if it's the wrong length; or you end up stuck with a few unusable stems hanging around your garage.

Make sure your saddle is set properly first, then worry about stem length. I agree with Clifton to try a few sizes at the LBS first, it would be a lot easier. Then buy one you need/order one.

You have to do this by trial and error, which could get expensive, but your estimate is likely to satisfy you, so get that.

Before messing with stem length, can you post a picture of your handlebars showing the position of the brake levers? Often, a significant change in reach can be had simply by re-angling the handlebars and/or brake levers.

Off the top of my head 80-90mm should be good. I am 6' and ride a 58cm top tube frame with a 90mm stem. Now I know that we might not have the same dimensions, but you say the 110 is a stretch and 110 is a stretch for me on a 58cm top tube. My advice would be to buy a cheap stem to try first or go to a bike shop and get sized.

I am in much the same position, once I have enough cash, I will probably get sized per xB_Nutt's suggestion.

sounds reasonable:

i am a shy over 6ft and one of my bikes as an 58.5mm top tube and i use a 100mm stem (with lots of drop)

I think this is good advice. First consider the position of your saddle. Google up KOPS, Knees Over Pedal Spindle. This is a good place to start.

Adjusting handlebar position by a whole inch is a lot. I'd be inclined to try a 90 mm or even a 100 mm stem and see how that feels.

Most folks think stems shorter than 90 look goofy. Try 90, make sure your bars are rotated level or up and shifters are high on the bends. If that's not enough there may be bars with shorter reach.