Best Bike Under $1500

Two very different goals here. Going to be difficult to find a compromise between the two regardless of money spent. I think I might go get a basic fitment just to know what size bike your going to be looking for. Find a good used bike for the commute and spend your hard earned money on a bike more appropriate for long distance endurance training.

Also maintenance, generally speaking is directly tied to mileage. The more miles your putting in the more maintenance you going to need. Whether you got a $600 bike or a $5,000 bike. They all require chain cleanings, lubrication, adjustments, tires and tubes, etc... Obviously the more expensive bike is going to have higher quality hardware so some of those things will be at longer intervals. But ALL bikes require basic maintenance. Good news is if you learn the basic skills, and invest in some basic tools, you can do almost all the maintenance yourself. 

Best wishes on your Ironman ambitions