Not sure what option to go for, but personally, I'd do it between the columns. After all, you can always move the sofa in the future whereas you cant with the columns

Hi, Although I love the way a mat really elevates the look of any artwork, in this case I think you should go with the smaller frames, forgo the mats and centre your three prints above where you position the sofa. Finally... please ensure that you don't hang the artwork too high above the sofa... You want the artwork to sit low enough so that you can appreciate it being seated... typically a foot or so above the back of the sofa, no more. Hope this helps.

Have you tried the taller, narrow table behind the sofa?
Then you could center the sofa on the wall, solving the "should I center pics between columns or over sofa dilemma", and allowing for some interesting pieces, lamp, vases, etc
behind the sofa to add visual, offset interest

Generally re: framing, I'd say go big. I've never regretted a little extra matting on a print. It will look great on that big open wall.
That said, I think you need to center over the sofa, otherwise it will look like it's in the wrong place. Set your art up to match how you use the room.
If you can center the sofa between the columns, you can do both, and I think that's the best bet.

Perhaps try turning the taller table so that it goes the length of the sofa's arm, which might allow the sofa to be centered on the wall too. If the dimensions don't work for that, I second the suggestion by Runwithscissors to try using that table behind the sofa for vases/photos. For framing, go big. The prints will look more substantial and it will give a little space between the print and the glass of the frame, which is supposed to be better for the life of the print.

How about angling the left table so it's kitty-corner with the couch and railing? Then you can center the couch on the wall and center the pictures about it. You can also position a large tree behind the kitty-cornered table to fill in the space and balance the height of the pictures.

Depends on what the prints look like, but with that height, I like the idea of going big and using the full width of the wall, and not limiting yourself to the size of the sofa.

Art almost always looks better with larger frames and mats. There should be at least 2-3 inches around the print (next time you go to a museum, check out how the work is framed.) I would try what Designa Gal suggests and put the table along the railing and perhaps get a small side table to go next to the sofa. I would center the three pieces on the wall, and then you'd be able to center the sofa too. And if the wall looks too crowded, you could put two above the sofa and the third elsewhere in the room - with matching frames they will still feel cohesive.

Definitely center the couch. I like the suggestion to turn the long table sideways against the couch, which will make it easier. If the table is longer than the couch is deep, you can push the couch out from the wall a little.

I also vote for big frames with mats.

We have a 83” long sofa with 3 of our 11x14" photos mounted in 21x25” frames. Going oversize made a dramatic difference. The photos had been mounted in small frames with 1" of matting for 20 years and had become invisible and so small that they were not important in the room. Now they really stand out in our living room. If there is a way for me to include a photo I will try to do so.

suggestion: center the couch on the wall, then center the prints above that. you can turn that little console sideways so it runs the depth of the couch arm. then set the lamp on it to raise the height of your light source.

Get some large paper (newspaper, butcher paper, or even construction paper) and cut it out in the frame sizes you are considering. Tape them up above the sofa and see how it looks--that way you can figure out what proportions that are pleasing without committing to anything. It's also the easiest way to hang pictures. In general, though, I think little mats don't look so great.

Go big, but do it differently instead of a boring, old-fashioned linear arrangement. Consider hanging them in an inverted-L with two-across and one-down. Then put a big lamp on the left side (photographer's left) table where the "missing fourth" picture would normally be. Having a 10-foot ceiling allows you to take advantage of the extra space, rather than having empty horizontal strips of wall above and below the artwork.

homebody and mginwa have offered the best advice. But it's also worth noting the truth of Patrick's words - without seeing this art it's impossible to state anything categorically. Is it abstract or representational? Is it simple or busy? Edgy or fairly conservative? A proper triptych or just three similar works? All of these issues determine how and where they are hung to their best advantage.

And "just say no" to "clever" methods of hanging artwork.