Personally, I would rank appropriate guidance and clear project management as more important than physical layout or various other "perks".

I'd disagree. I'd put them on equal footing. A bad working environment can cause just as many problems as bad "management". No matter how good the management you cannot be productive in a poor working environment.

For example, I was once forced to work for a couple of months in an open plan office next to a group of marketing people. Lovely people (well, most of them :-) but their jobs involved answering and making phone calls all day. Our productivity dropped to just above zero with six mobiles and six desk phones going off continuously.