Get one with a two speed fan that osculates, it will keep things warmer by distributing the heat better. We put one about a third of the way down our 40' DP and it gets some heat all the way back to the bedroom.
Also, especially because you have dogs, get one that shuts off when tipped over. I think they're all supposed to have this safety feature now days, but test it. If it doesn't shut off to your satisfaction take it back and get a different model. And test how hot the front of it actually is. Will it burn the dogs or their hair if they touch it. Most units with fans won't, but again test it.
Bill