Assuming the snow has been good then there are runs through the trees but probably best going with somebody who knows them and is prepared to take you. I've done a few of them but they seem to change each year. Again, assuming the conditions are right there is a lot of what you could call off piste but it's not that extreme however under the Gondola is fun. I suppose if you are a bit mad you could try under the chair lifts in a couple places. The snow park is good if you like that sort of ...
Assuming the snow has been good then there are runs through the trees but probably best going with somebody who knows them and is prepared to take you. I've done a few of them but they seem to change each year. Again, assuming the conditions are right there is a lot of what you could call off piste but it's not that extreme however under the Gondola is fun. I suppose if you are a bit mad you could try under the chair lifts in a couple places. The snow park is good if you like that sort of thing, I suppose it has all the usual stuff like rails and so on and last season it some massive jumps. Avoid the middle of Feb if you want to avoid UK half term and generally the snow is good from back end of Jan to the end of the season in March and sometimes beyond. There are plenty of places to stay, each to their own but if you ask Kas she will be able to suggest a few places, depends what you want really. As you aren't going in half term I wont see you but I've got a nice little apartment in the centre of the resort via booking.com when I go next year.
I think that I should add that there is an area of off-piste which people call the 'Avalanche' , I think last year it claimed two people and the year before 1. Prior to that it has taken some very experienced people. You really don't want to underestimate some parts of Borovets