@Sharad M. $250 paid by myself may be high if it is for a GC I've worked with before and is likely to get future work. But my feeling is that I should be willing to pay more for something that has such a huge impact for the rest of the project. I will be using contractor A's estimated costs and schedule to come up with my maximum offer amount. Once an improvement plan is made, I bid that out to several general contractors (including contractor A). I pick the one I feel is best to complete the project. That would be contractor B. So I think you've helped me answer part of my own question. Contractor B's expenses are already included in the total cost of the project.
@Tom Brunell It's a double edged sword I guess. You make a good point. With bidding wars, maybe there's less sense of loyalty between investor and GC, but I don't know any GC's well enough to be loyal to any of them yet. One huge advantage to bidding is that it keeps everyone competitive through checks and balances. I've seen problems with sole sourcing in my industry when we as a utility hire many contractors. Fees creep up for the ones that get sole sourced.
@Patrick T. Thanks for the advice. I will definitely ask those with experience for GC referrals. You said that you as a GC would make a proposal for an investor differently than a private remodel. How do you mean? As for your last few points, I agree that each bidder should get a walk through with me (and the initial contractor, contractor A) so that they can get a full understanding of the project. Does that seem like a good idea? Any other suggestions? My predicament is that I can't rely on myself for accurate estimates and I have a separate full-time job so I really need to rely on general contractors.