Interviewing Builders - the right questions to ask?

This month is 'find our builder month'. I have a fistful of prospective builders/general contractors that I have met, talked with, or at least emailed. I will be meeting them, reviewing their work, and checking references. In doing so, I'd like to be sure that I am covering as much ground as possible before I sign the dotted line and formally make a selection.
Any suggestions as to the initial topics that I can dive right into that could reveal any red flags or set off alarms?
Also, how forward should I be with our 'modern' design ideas? Should I try to avoid scaring off a good builder by masking some ideas or should I just lay my cards on the table right away?

Definitely lay your cards on the table at the begining. Being up front will promote a good working relationship. The only way you'll be able to tell if they can do what you want it to tell them what you want. Ask if they've done projects of similar scale, level of detail, etc. Be up front and ask for their take on your modern ideas. You'll be able to judge by their response weather or not you'll be able to work with them. Ideally you'll find a contractor who is interested in modern design as well.

I agree. By being up front and clear about your ideas and expectations, you'll get a much better idea about what you could expect from the working relationship. It doesn't really matter if the person LIKES your ideas, but simply that they are recptive to them and seem willing to cooperate and work with you to achieve your desired result.
You're likely to encounter a fair amount of fear/resistance/misconception when it comes to doing something outside the box (i.e. modern), but by being clear, straightforward and, most important, as knowledgable as possible, you'll spot the losers pretty quickly.
I've also learned to trust my gut. Keep your BS filter turned up to high and always take the time to study up on anything you don't understand.

I just wanted to reiterate what Splatgirl said. Pay attention to your instincts and also try to find someone who loves their profession and your project. Also, learn as much as you can not only to prevent getting ripped-off but also so you will be able to understand issues of cost and time.

I'm completely behind comments others have made re: being up front with your expectations and desires, asking about similar projects they've done, etc. Some other things you might consider:

Try to get a look at projects currently under construction, even small ones. How does the site look? Construction makes a big mess, but a relatively tidy site (in comparison to other builders) may be an indicator of a better-run project. Are people there, working? Swing by over the course of a few days to check. Sites that lie fallow for long periods are frustrating to the owners! Unless of course the builder is working on his or her own house, then it's excusable.

You might ask questions about the builder's subs -- does he or she have a good, ongoing relationship with reliable subs? You should ask former customers how satisfied they were with the subs, too. If I had listened more carefully to precisely this feedback, I could have avoided an unpleasant experience with a concrete contractor -- but that's another story!

Good luck! I hope you have fun with this.

Your responses are very helpful...how helpful will be decided during the next ten days or so when we meet with at least four of the targeted builders!

In addition to asking about subs, I would ask about crew composition: what kinds of guys, how big, how often on site, site super's experience. I would also ask about invoices and payment: the more organized the invoice, the more trustworthy the builder.

I would also talk with them expecially about the craftmanship, and see if you can visit completed projects and talk to the owners.

one meeting completed. It went pretty well - we met at a 95% complete home and things were in good shape (the home, the site, attitudes, etc.).

This first guy did a good job presenting his credentials and personality, which was nice. He gave both my wife and I equal time and attention. He likes our interest in doing something a bit left of center and even admitted he was tired of some of the standard things he includes in every home he builds. He like our low pitched roof ideas, steel roofing, and fiber cement siding - but he was a bit wobbly on the concrete floors. I think this was mostly due to our inclusion of a radiant heat system.

So, just one 'iffy' item with this guy.