If I've got a site that has some funky access issues, or some complicated logistics (need to get a bunch of contractors to work together on a tight schedule?), I always call for a pre-bid site meeting for the major contractors, and then require a detailed explanation of how, exactly, they plan on doing the work as part of the bid response. That way, there are no surprises on either end. And no surprises = no additional costs/contract wiggle room.
I occasionally got some push-back from other managers who didn't appreciate all this time spent on the front end. That's pretty easy to combat - one site visit can eliminate a huge waste of time and effort if you find out that the original plan is untenable. Better to find that out before you have a drill rig and a big crew idling in a vacant lot.
However, I also ran into some issues with managers who didn't believe in pre-bid meetings on principle. They were convinced that all the subcontractors would exchange cards after leaving the meeting and conspire to submit uniformly high bids. Here's the problem with that: in my area, the identity of the other contractors expecting to bid on a particular project isn't much of a surprise. It's a small industry. When I try to get work, I have a pretty good sense of who my competitors are and our relative strengths and weaknesses. Same thing with contractors. Maybe someone's a little thin on work one month, and so they'll have an unexpectedly low bid to keep the equipment running. Maybe another contractor thinks that he's got an in because I've sent a bunch of work his way, and he jacks up the prices. So having everyone meet at the site doesn't change any of the underlying dynamics between contractors.
I probably only decide that I need a pre-bid meeting for 10% of the projects I start up. But I'll fight to keep the meeting for that 10%.