I have a very similar home without the port unfortunately. I think square pillars would look best. Can i ask how you deal with the dormers upstairs ? I'm having a hard time with the bedrooms.

Either seems like they would work - but something beefy for sure. You can get faux columns at many home centers and could try them out that way. Set them next to the center columns and just prop them up - one of each style.
I would suggest something vertical surrounding your front door to beef that up as well - perhaps side lights, faux shutters, vertical potted plant, etc.

I think either would work. To me, round ones would give your house a little more "formal" feel, while the square type seems more farm house. So, it depends on whether you want to dress up, or be casual. :)

Here is a house with more substantial square columns.

Larger square columns will give the porch a more substantial look. You may want to do recessed paneled columns with base and crown.

We are building a new ranch house in the country and have gone with 10x10 square columns on the porch with no railing.

Definitely square.

Square ones for sure.

Squares with groove mark in the centre from top to bottom on all sides .

Going in a different direction, take a look at shingle style/craftsman porches, where it is a wide basesome with stone, other with siding, and somewith a column on top. my reasoning is that by the pictures, the house looks a bit top heavy, and a very solid base would ground the dormers. expensive option, but worth it

a few examples:





or go to this website http://buffaloah.com/h/br/mktsq/mktsq.html
and look at 100 Amherst St. / Sander/ Braun House

Great suggestion William, would love to see some craftsman details.

We are doing the same thing at our house. We really wanted to switch to "beefier" columns, too, but can't do it without changing the structure above (beam isn't wide enough for larger posts, and also the post will hang over the front of the porch at the bottom if any larger.) Just something to consider! Good luck!

Thank you William Hill Cawood! I will do that this weekend!

Square,
look at the classical orders on how a column relates to the beam, you may have trouble on the exterior side of the porch if the floor does not extend far enough past the beam for the column base to fit. Express the capital detail past the beam, not under it.
Square columns can be paneled to add greater detail. The paneling adds interest as one moves closer to the house.

A couple of observations,
Window trim could be wider,
Your steps are wide but the walk is not. Consider a wide landing to transition to the walk.
The porch windows look very short, maybe some kind of under window paneling, new trim can go to the floor and frame for the panle.
Shutters add detail. I do not think I would add shutters to the short windows as it would exagerate the horizonal. Add them with under panels. Or just add trim to the front door.

Wow! Dytecture's photoshop pic is amazing! I love the look of the chunkier square posts with your house, Amy! What a fresh new look to a already lovely colonial home! If any of you have time to look at my dilemma I'd really appreciate it, you, too Amy =) It's titled... "How do we get beefier porch posts...?"

I agree with Don Duffy Architecture: ask Vitruvius. Although the money would be better spent improving the ground floor fenestration.