I have been running for 30+ years at this point.
* There is not going to be a perfect device. As the saying goes, a Swiss Army Knife is no replacement for a well stocked toolbox. A few dedicated devices will do the trick much better than an all-in-one device will.
* While listening to music while running can make the time go a little faster, a running partner will be a much better addition. When it is dark and snowing outside and you are warm and in your bed, knowing that someone is going to be meeting you in 30 minutes is better motivation than anything else. Training should also always allow you to talk while you run (otherwise you are going too fast). Having someone there to talk to makes sure you are going at the right pace.
* Once you have some experience with them, a heart rate monitor can really guide training. Pace can be affected by ambient temperature, wind, inclines, and other factors. Your heart rate is a better indicator of effort.
* I have not had the Forerunner 15. I have had the FR60, the ForeRunner 405, and the ForeRunner 220. All of them have been able to get 3+ hours. The 405 was the worst of the bunch, but that was a relatively early GPS watch. Even then, it got 3+ hours for the first year or so. The 220 gets 6+ hours - I have honestly never gotten the battery down very low. Even after 3+ hour runs, it is showing more than 50% left. I generally use the 220 for 3-4 runs before I consider charging it back up.
* I never run with my phone. It is partly because of bulk, and mostly because I go running to get outside and get away from the always-on world we live in. I only listen to music on my long runs, and for that I have an older iPod Shuffle.
* As others have mentioned, http://www.dcrainmaker.com/pro... is the best review site out there.
* Based on your needs, I would consider Garmin's newest watches, the 230 or the 235: http://www.dcrainmaker.com/201... I would also purchase an iPod Shuffle. If wireless is a big requirement, I would look at the iPod Nano and BlueTooth headphones.