We did a intl-domesitc connection in summer. Ours was UA-UA, but it doesn't really matter, as either way, you have to come in through immigration, which is quite a long walk, then take train back to B (unless you get one of the few UA departures in A).

Personally, I love DEN as an airport, and has great amenities, but because you basically have to walk from arrival gate (presumably in A) back to the main part of the terminal, clear immigration, then take the train back to departure concourse, it is a bit of a PITA. Ironically, there is no way to walk, as a departing passenger, from security to any of the gates, but arriving internationally, there is no other way but to walk. I don't know how long we were walking for, but I'd say a good 15 minutes at least (disclaimer: I had my 9 and 6 year old kids with me, so realistically, if I was traveling myself, walk would have been faster). Realistically, especially when with the kids, I'd tend to avoid an international - domestic connection at DEN if there was a choice.

To add insult to injury, once we cleared and came back through security, the close checkpoint to where you come back into the main terminal was closed, meaning the main CLEAR/Precheck lane was closed, and we had to walk over the other side. Why DEN closes one of the security checkpoints at like 7 - well before UAs last bank of flights, at least west - is beyond me.

I'm not sure what I-D connection time at DEN actually is, but for the average walker, and someone who may not be familiar enough to navigate DEN without stopping to look at directions, I'd say I absolutely would not advise less than 1:30 connection, and probably close to 2 to be comfortable. Honestly, with an on time arrival, you should be fine...just note there will not be too much time to relax between flights.