I think Vintage Woodworks sells parts in cedar or cypress, much more rot-resistant choices than poplar. I wouldn't use poplar outside. I used their materials for two porches and thought the look was great. Their dimensions and shapes were much better than the lumber yard offerings. People (albeit relatively clueless) thought our house was the old farmhouse left in the middle of the development, exactly the effect I was hoping for. By priming and painting all of the parts with oil-based paint prior to assembly I got a finish that has gone 10 years in New England so far. (The railings and porch posts the builder originally installed were rotten within three years. Partly due to crappy lumber and partly due to incompetent installation.)

There's PVC and then there's PVC. I haven't looked at their parts recently. If they are an Azek-like cellular PVC that you can paint then I would expect them to look quite nice, probably indistinguishable from wood. Paint on cPVC lasts a long time. If they are the shiny plastic common at the Borg that you can spot from a mile away there's no way I would put it on my old (or new) house.

Cedar or nothing at all.

No matter how you dress it up, PVC looks like plastic.

Thanks folks.... unfortunately cedar is out of the budget, We're already being WAAAYYYY to perfectionist on this house and have to keep reminding ourselves that it's a rental, not our home.

You know - I have a rental (live in 1 apt and rent out the rest). Your making the place look good makes the neighborhood look good... which increases the desireability of your units. I could go on about other reasons why its to your benefit to put some extra care, love and $$$ into your project. Not go hog wild, but not to be super tightwad either.

On to my comments re: the topic. I think the poplar will be just fine if are vigilant about keeping it painted - Ive used it for some of my exterior porch repair for much the same reason. Before you assemble the pieces seal the end grains. Part of your routine as landlord should be to regularly inspect your paint/caulking around the porch (and that bathtub that you m entioned in another thread)

Cedar isnt the only rot resistant wood - and its only rot resistant, not rot proof so it still needs to be maintained. Cypress and green treated pine may be more more affordable options.

This is more a question than a statement - I bought some cedar 1 inch boards for something and I was shocked at how light weight and splintery it was - and really soft. I was expecting something heavy and dense like the original old growth cedar of my porch posts. Is this typical of modern cedar.... or are there different types, or what? If this is typical, OP indeed might be better off with the poplar - which would be denser & not as soft & porous. Again this is more of a question than a statement.

PVC looks like plastic but will look better if it is painted. THE BIG PROBLEM however is railing height. The hand rail MUST NOT be higher than the window sill. There is a lot to say about this so go here for more info.http://www.oldhouseguy.com/porch-railing-height/ 

It's probably not a good idea to put an illegal railing on rental property.

Thanks for the input, guys. I checked with my code inspector and in our town you don't even NEED a railing if the deck is <30" from grade. I've decided to do a kneewall railing at 30" high.

Sadly, it will be higher than the sill. I am cognizant of that rule ;) The sill is like 23" I think. Too low for a knee wall, which would then look out of proportion with the posts and frieze, don't you think? Using classical proportions for those elements, The kneewall comes out to 30" high. It looks about right, too, when compared to other homes of this period/style with similar kneewall/post porches. here's an example in a nearby town.

It looks very closed in. I would make it 25-26"