Well, ... that was educational. We covered quite a bit of ground.
The family visits are not a problem as we have a guest house (where we used to live) that is not part of the B&B, so there is always room and no IRS issues. We have private dining space, too for a few family.
The problem was with friends. Nearly all say they want to pay for their room because this is now my livelyhood (as if!), but 1) that makes me feel commercial if I invite them to stay and 2) the rooms can be spendy for some folk.
When I invite people here, I explain that housekeeping, breakfast, and misc amounts to $40 to $60 per room for a few days and that $ contribution would level the field. People can easily pay that and at least feel that they are not taking advantage of me; conversely, I am not profiting from them. Evening food and wine is a potlatch anyway.
I think that the suggestion of offering the "corporate rate" to friends of friends or acquaintances who invite themselves is fair, as it is their decision to come when they do. That is about 15 to 20% off.
As for the matter of entertaining visitors ... that is where all the self guided tourist info comes in handy.
Thanks to all who commented.