I am to travel to the US (from the UK) for a meeting relating to some work I have been doing. If the meeting does not go well I shall have to return to the UK soon after the meeting and fix the thing I have been working on. If it all goes well I shall take an extended holiday after the meeting, possibly up to 6 weeks, possibly all in the US, possibly travelling further afield. I have a brother in the US who I am likely to spend some of the time with. I shall have a return ticket, but I will not use the return segment if I extend the trip.
When I arrive in the US I expect to be asked "How long are you staying in the US" at passport control. It would be easy to say the duration of the meeting. I could explain my situation and the uncertainty involved in the length of my trip, but it seems like it would wave some red flags; extended stay, uncertainty, longer away from work than is usual especially in the US. I am worried to go into all this detail will cause problems. However lying to the immigration officials could cause worse problems if that dishonesty is identified.
Is honesty the best policy in this situation, or should I tell them the easy story which may well turn out to be true, but may not? I am interested in minimising the chance of trouble, especially any trouble that will interfere with my ability to travel to the US.