Another thing you can do is talk to others who have gone to the trainer you are thinking about using. If they have a website there are often testimonials included and sometimes there are e-mail links you can use. As far as the facility itself, the one that I go to has classes both inside and out. Last summer when Bella was in CGC class we often met at different local parks. All the activity and sounds were great ways to get her used to doing what I wanted her to do even when there were things going on that she would much rather do. Good luck finding a trainer you like. It is tremendous fun and a great way to bond with your boxer!
Bella 6/13/06 CGC, TDI
Jake-border collie/beagle 6/20/99 & Reggie-Jack Russell 12/25/97