I have done this four times thus far. 3 of them were good or very good experiences, and the fourth was abysmal. Would I do it again? Yes, but only with people flying in from the same time zone or only 1 or two time zones away at most.
-- Modified on 11/9/2015 9:03:25 PM
I've done it and you should definitely offer it. Typically, the client will pay expenses upfront and maybe a little extra for your travel time.
The biggest potential headache are issues with the airlines, so avoid that aggravation and decline any request with a tight schedule.
As anyone knows on here, ladies get requests to accommodate unreasonable travel for 1 or 2 hour appointments. If anyone knew what went into a tour, and how many times you have to visit a city in order to make decent money, they would understand.
What I have done is refer them to my travel and/or benefaction page, which gives details on what would get me to come to their area. (A fly me to you date package.)
It has worked having that available on numerous occasions, but usually for people who see it and book it, rather than the ones who asked me to visit their area for a tour. The ones I usually get are ones who have traveled to Chicago, and ask me to travel with them or to them. It's fun, but I have learned to make sure I cover my ass and charge what is worth going. I definitely don't want to be irresponsible with my planning, as a free tropical vacation sounds nice, but it doesn't pay the rent.
Dual purpose, and a wonderful tool. But yes - definitely charge for all of the "hiccups" that happen in a trip, because if you're not careful, you could lose money on it. It's only one date, not a tour with five dates, so the loss is heavier and a huge bummer if you don't charge for emergencies, extra time, and / or unexpected expenses, like expensive taxis, lost items on flight, and the toiletries you don't want to pack in your suitcase.
I honestly (as we all probably do) get a lot of "But I really want to see you! I've wanted to for a long time!" Well, I would love to see him too, but I can't be stupid about it lol. Hence, the fly me options. 
-- Modified on 11/10/2015 2:58:33 PM