we're lucky in the sense that we have heat and air conditioning at our facility but i do know that not all facilites have heat and a/c. that was important to me because i don't like the heat of the summer and neither do our dogs

and hubby isn't too fond of chilly temperatures. so temperature control played a big part in our choosing the facility. (after the training methods, of course

)
our facility also has matted floors. matted floors are VERY important if you are going to be training your dog to go over jumps. you never want to jump a dog on a bare floor....or if you are training outside...you don't want to jump them in damp/wet grass. they will get hurt from sliding, landing wrong or not be able to take off over the jump the right way.
i prefer indoor classes as opposed to outdoor because of weather (rain, snow, etc).
i totally agree with RoxiesEcho.....training is a lot of fun and a great activity to bond with your dog. we are having a great time with our two boys. a lot of people that have never attended obedience with a dog always ask us when we are going to be able to stop going to training. we try to explain that as long as we and our dogs are having fun...we'll continue to go for a very long time.
there's so much to learn and so much fun to be had that we look forward to our class each week. it's really therapeutic for me. i'm so tuned into working with Moby that my mind is cleared of any of the stresses of everyday life. yes...there are times when we and/or our Boxers have an "off" day at training but we never care about that or take it to seriously. maybe we won't work on anything new that night. instead...we just take it in stride and try to find a way to make it even more fun for the dogs to learn so we always end on a positive, happy note.