If you are thinking about getting another dog, but just don't have the time for full-blown training regime, why not consider adopting an older or senior dog?
There are many older dogs out there looking for a nice home to spend their last few years. A place where they can be loved, fed and cared for. Somewhere they can call home.
Most senior dogs don't require much housetraining, likely won't chew excessively, don't require as much exercise as the "young pups" out there and will likely be calmer than a younger dog. Yes, there are always exceptions to these rules, but most are going to be quite easy to train - provided you aren't looking for a sport dog or a dog to learn 1001 tricks.
There are currently 6059 Boxers available for adoption on Petfinder. The Rescue I choose to Feature is Sly, a 10 year old boxer. Sly is reportedly good with other dogs, kids, cats and "everyone". He is currently located in Newark, OH and is fostered by a group called "Stop the Suffering".
I couldn't find any info about this group other than that they pull animals out of kill shelters and foster them until they are adopted. Dogpile search came up with little to no info other than their petfinder pages, their website, and their old website which has been redirected to the new one.