Is this a 'final presentation' type render, or something you will be producing a lot?
We render most of our impressions at 300 dpi 195x135 mm. This still prints out fine at full size on A4 paper (assuming you have a decent enough printer).
It's also slightly larger than HD, so will look fine on screen too.
If it's something that's ok to run for hours over night and you aren't too bothered with those hours, then of course you can go all out.
However, I would consider having a setup that also allows you to output exterior renders in under 5 minutes and interior renders in about 10 minutes.
My workstation has much worse specs and pulls this off, by starting off with the 'fast' physical render presets and just adjusting a few settings.
Erwin Edel, Project Lead, Leloup Architectenwww.leloup.nl
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