Mike.....
I recommend getting a contractor on board from the very start....before design even starts and go the negotiated route with him/her regarding price over a competitive bid set-up.
The reasons for this are:
-As Charles mentions above for a competitive bid to mean anything the plans usually have to be a lot more detailed. That usually means a lot more decisions have to be made by the owner upfront and usually leads to decision overload. And that usually leads to more changes during construction (see more on that below).
-Having a builder on board from the start goes a long way toward keeping cost in line. As an architect I know a lot about cost but don't profess to know as much about them as someone who's getting sub bids everyday (and as an aside, the builder may know something about design but he doesn't know as much as someone who's main focus IS design although many believe they do). If the builder is at the table during design, cost questions can always be considered, often generally, sometimes specifically but they can be addressed.
-With any builder, whether a "winning bidder" or one negotiated with, there better be a healthy amount of TRUST or the whole relationship is not going to be a happy one. You're not buying a car here where your relationship with the dealer lasts a few hours before you drive off the lot in your brand new car. You're going to be joined at the hip for the better part of a year, maybe longer, so you better feel VERY comfortable with the individual. In a competitive bid situation, interviewing a builder for a few hours can't compare with being involved with one during the ENTIRE design and construction doc phases lasting typically several months.
-We're building a custom home here, not a 7-11 and as such there's a tremendous amount of emotion involved. There will be changes due to that and other changes will be the result of decisions made months earlier so we could have a comprehensive "bid" set. And all those changes, both up and down, will be negotiated with the "winning bidder" on a non-competitive basis. If you're going to be negotiating at some point with ANY builder, why not answer that question of TRUST early in the process and take advantage of a knowledge source from the very start?
-Of course, the obvious question here is "If the price is negotiated, how do I know I'm not getting screwed?". Excellent question but then that goes back to the issue of TRUST, an intangible that's part of every successful relationship, whether personal or professional. And of course working with a builder for months before the first shovelful is turned goes a long way towards answering that question.
-And finally, let me conclude by saying that getting "competitive bids" tends to put the focus on price only. And as I said above, we're building a custom home here not some utility building where price only may be a good approach. Let me cite an observation by John Ruskin, an economist and a bunch of other stuff a hundred years ago. He called it "The Common Law of Business Balance":
"There is hardly anything in the world that someone cannot make a little worse and sell a little cheaper, and the people who consider price alone are that persons lawful prey. It's unwise to pay too much, but it's worse to pay too little. When you pay too much, you lose a little money, that is all. When you pay too little, you sometimes lose everything, because the thing you bought was incapable of doing the thing it was bought to do. The common law of business balance prohibits paying a little and getting a lot, it can't be done. If you deal with the lowest bidder, it is well to add something for the risk you run, and if you do that you will have enough to pay for something better."
I may write more later on the best way to set up a builder and architect but I'm too busy today and have already gone on too long anyway.
But good luck in your build. Exciting times ahead!
Q