Much as I hate to do it, I have to agree with Roger. I have seen various management statistics that said it requires a MINIMUM of $600-$1000 in positive advertising to offset the negatitve actions of ONE irate customer. That was before the internet gave said customer a much larger audience for his gripe.
If you have a questionaire ready for those people booking tours that asks the right questions, and then make the info available, when it is appropriate (Especially contact persons of fund raising type charters) You'll THEN be doing the bare minimum of the job. Yes it IS the tour director's job to advertise his charter, but it is the railroads job to run as many full trains as they can, so, if people call asking about a specific charter, it is very shortsighted not to give whatever information the organizer allows.
Computerizing of the bookings is an excellent idea. Obsolete first and second generation pentiums are dirt cheap, and quite capable of doing the job, especially when networked. In this case the money spent would be quickly earned back through increased efficiency. Perhaps having someone available to answer questions during off days and hours might not be cost effective, but an answering system with a few menu options that can give general info such as departure days, times, prices, even directions from nearby major cities is almost a must if you don't have a live body. The customer is the ONLY reason that counts for even operating a railroad (or any business), great locs, track, food, and etc., won't mean squat if nobody is paying to come see it. Think twice before brushing these problems aside. There was enough negative advertising during the transition, the operator cannot afford to lose more customers through carelessness.