I am flying United LGA-DEN-LGA in early June to pick up a puppy. I'm in 1st on a 737-800 both ways-- 2B LGA-DEN; 4E DEN-LGA (the only available aisle). I know there is no recline in 4E. My concern is that on the website a photo of the cabin interior shows a bar down the center of the back of 3E making it difficult to place the carrier. Can anyone confirm whether or not there is a bar (the United rep had no idea)? Also, the United rep strongly suggested that I switch to a window seat. Any advice on which seat to pick would be most appreciated. I have never flown with a pet before and am more than a little nervous about it. Thanks!