For dedicated triathletes, the Garmin Forerunner 920XT GPS watch is an excellent training tool, one that I’ve really enjoyed using over the past couple of years, despite it’s size… however it does fit relatively well, but it’s not the sort of watch you’re going to wear socially.
The watch is on the expensive side, but you’re paying for it’s vast amount of features and given you’re going to be spending a lot of time with your Garmin 920 XT it could prove to be a worthwhile investment!